möbius transformations - cedar crest college · i möbius transformations are defined over the...
TRANSCRIPT
![Page 1: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/1.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Möbius Transformations
James M. Hammer, III
May 1, 2008
James M. Hammer, III Möbius Transformations
![Page 2: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/2.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
IntroductionInformation on Complex Numbers
Cardinal FormsDefinition of Möbius TransformationsComposition of Möbius Transformations
Circle Preserving PropertyDefinition
Relationship to SphereStereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
ConclusionWrap-up
James M. Hammer, III Möbius Transformations
![Page 3: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/3.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Numbers
I Möbius transformations are defined over the Complexplane (denoted C.)
I Algebraically, the equation, x 2 = �1 should have asolution.
I Imaginary Unit: i =p�1.
I A complex number, z , can be expressed in the formz = x + iy for real numbers x and y .
I x is called the real part of z (Re z = x .)I y is called the imaginary part of z (Im z = y .)
James M. Hammer, III Möbius Transformations
![Page 4: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/4.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Numbers
I Möbius transformations are defined over the Complexplane (denoted C.)
I Algebraically, the equation, x 2 = �1 should have asolution.
I Imaginary Unit: i =p�1.
I A complex number, z , can be expressed in the formz = x + iy for real numbers x and y .
I x is called the real part of z (Re z = x .)I y is called the imaginary part of z (Im z = y .)
James M. Hammer, III Möbius Transformations
![Page 5: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/5.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Numbers
I Möbius transformations are defined over the Complexplane (denoted C.)
I Algebraically, the equation, x 2 = �1 should have asolution.
I Imaginary Unit: i =p�1.
I A complex number, z , can be expressed in the formz = x + iy for real numbers x and y .
I x is called the real part of z (Re z = x .)I y is called the imaginary part of z (Im z = y .)
James M. Hammer, III Möbius Transformations
![Page 6: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/6.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Numbers
I Möbius transformations are defined over the Complexplane (denoted C.)
I Algebraically, the equation, x 2 = �1 should have asolution.
I Imaginary Unit: i =p�1.
I A complex number, z , can be expressed in the formz = x + iy for real numbers x and y .
I x is called the real part of z (Re z = x .)I y is called the imaginary part of z (Im z = y .)
James M. Hammer, III Möbius Transformations
![Page 7: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/7.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Numbers
I Möbius transformations are defined over the Complexplane (denoted C.)
I Algebraically, the equation, x 2 = �1 should have asolution.
I Imaginary Unit: i =p�1.
I A complex number, z , can be expressed in the formz = x + iy for real numbers x and y .
I x is called the real part of z (Re z = x .)
I y is called the imaginary part of z (Im z = y .)
James M. Hammer, III Möbius Transformations
![Page 8: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/8.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Numbers
I Möbius transformations are defined over the Complexplane (denoted C.)
I Algebraically, the equation, x 2 = �1 should have asolution.
I Imaginary Unit: i =p�1.
I A complex number, z , can be expressed in the formz = x + iy for real numbers x and y .
I x is called the real part of z (Re z = x .)I y is called the imaginary part of z (Im z = y .)
James M. Hammer, III Möbius Transformations
![Page 9: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/9.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Algebra
Let z = x + iy and w = s + it , where x ; y ; s ; and t are realnumbers. Then, the following operations are defined as follows:
I Addition: z + w = (x + s) + i (y + t).I Subtraction: z � w = (x � s) + i (y � t).I Multiplication: zw = (xs � yt) + i (xt + ys).
I Division:zw
=wzww
=(xs + yt) + i (ys � xt)
s2 + t2 ;w 6= 0.
I Modulus (distance from the origin): jz j = px 2 + y2.
James M. Hammer, III Möbius Transformations
![Page 10: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/10.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Algebra
Let z = x + iy and w = s + it , where x ; y ; s ; and t are realnumbers. Then, the following operations are defined as follows:
I Addition: z + w = (x + s) + i (y + t).
I Subtraction: z � w = (x � s) + i (y � t).I Multiplication: zw = (xs � yt) + i (xt + ys).
I Division:zw
=wzww
=(xs + yt) + i (ys � xt)
s2 + t2 ;w 6= 0.
I Modulus (distance from the origin): jz j = px 2 + y2.
James M. Hammer, III Möbius Transformations
![Page 11: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/11.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Algebra
Let z = x + iy and w = s + it , where x ; y ; s ; and t are realnumbers. Then, the following operations are defined as follows:
I Addition: z + w = (x + s) + i (y + t).I Subtraction: z � w = (x � s) + i (y � t).
I Multiplication: zw = (xs � yt) + i (xt + ys).
I Division:zw
=wzww
=(xs + yt) + i (ys � xt)
s2 + t2 ;w 6= 0.
I Modulus (distance from the origin): jz j = px 2 + y2.
James M. Hammer, III Möbius Transformations
![Page 12: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/12.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Algebra
Let z = x + iy and w = s + it , where x ; y ; s ; and t are realnumbers. Then, the following operations are defined as follows:
I Addition: z + w = (x + s) + i (y + t).I Subtraction: z � w = (x � s) + i (y � t).I Multiplication: zw = (xs � yt) + i (xt + ys).
I Division:zw
=wzww
=(xs + yt) + i (ys � xt)
s2 + t2 ;w 6= 0.
I Modulus (distance from the origin): jz j = px 2 + y2.
James M. Hammer, III Möbius Transformations
![Page 13: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/13.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Algebra
Let z = x + iy and w = s + it , where x ; y ; s ; and t are realnumbers. Then, the following operations are defined as follows:
I Addition: z + w = (x + s) + i (y + t).I Subtraction: z � w = (x � s) + i (y � t).I Multiplication: zw = (xs � yt) + i (xt + ys).
I Division:zw
=wzww
=(xs + yt) + i (ys � xt)
s2 + t2 ;w 6= 0.
I Modulus (distance from the origin): jz j = px 2 + y2.
James M. Hammer, III Möbius Transformations
![Page 14: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/14.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Complex Algebra
Let z = x + iy and w = s + it , where x ; y ; s ; and t are realnumbers. Then, the following operations are defined as follows:
I Addition: z + w = (x + s) + i (y + t).I Subtraction: z � w = (x � s) + i (y � t).I Multiplication: zw = (xs � yt) + i (xt + ys).
I Division:zw
=wzww
=(xs + yt) + i (ys � xt)
s2 + t2 ;w 6= 0.
I Modulus (distance from the origin): jz j = px 2 + y2.
James M. Hammer, III Möbius Transformations
![Page 15: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/15.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Theorem 1.1
Theoremz z = jz j2
Proof.
z �z = x 2 + y2 + i (xy � xy) Multiplication= x 2 + y2 Additive Inverse
=�p
x 2 + y2�2
Square Root= jz j2 Modulus.
James M. Hammer, III Möbius Transformations
![Page 16: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/16.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Theorem 1.1
Theoremz z = jz j2
Proof.
z �z = x 2 + y2 + i (xy � xy) Multiplication
= x 2 + y2 Additive Inverse
=�p
x 2 + y2�2
Square Root= jz j2 Modulus.
James M. Hammer, III Möbius Transformations
![Page 17: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/17.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Theorem 1.1
Theoremz z = jz j2
Proof.
z �z = x 2 + y2 + i (xy � xy) Multiplication= x 2 + y2 Additive Inverse
=�p
x 2 + y2�2
Square Root= jz j2 Modulus.
James M. Hammer, III Möbius Transformations
![Page 18: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/18.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Theorem 1.1
Theoremz z = jz j2
Proof.
z �z = x 2 + y2 + i (xy � xy) Multiplication= x 2 + y2 Additive Inverse
=�p
x 2 + y2�2
Square Root
= jz j2 Modulus.
James M. Hammer, III Möbius Transformations
![Page 19: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/19.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Information on Complex Numbers
Theorem 1.1
Theoremz z = jz j2
Proof.
z �z = x 2 + y2 + i (xy � xy) Multiplication= x 2 + y2 Additive Inverse
=�p
x 2 + y2�2
Square Root= jz j2 Modulus.
James M. Hammer, III Möbius Transformations
![Page 20: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/20.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Definition of Möbius Transformations
I A Möbius transformation is a rational function of the formH (z ) =
az + bcz + d
for a ; b; c; and d in C, where ad � bc 6= 0.
I The restriction on the determinant (ad � bc) is for the sakeof the derivative (slope of the tangent line), which is
H0 =ad � bc(cz + d)2
.
I If the determinant would be allowed to be 0, then theoriginal transformation, H, would be a constant function.
James M. Hammer, III Möbius Transformations
![Page 21: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/21.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Definition of Möbius Transformations
I A Möbius transformation is a rational function of the formH (z ) =
az + bcz + d
for a ; b; c; and d in C, where ad � bc 6= 0.
I The restriction on the determinant (ad � bc) is for the sakeof the derivative (slope of the tangent line), which is
H0 =ad � bc(cz + d)2
.
I If the determinant would be allowed to be 0, then theoriginal transformation, H, would be a constant function.
James M. Hammer, III Möbius Transformations
![Page 22: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/22.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Definition of Möbius Transformations
I A Möbius transformation is a rational function of the formH (z ) =
az + bcz + d
for a ; b; c; and d in C, where ad � bc 6= 0.
I The restriction on the determinant (ad � bc) is for the sakeof the derivative (slope of the tangent line), which is
H0 =ad � bc(cz + d)2
.
I If the determinant would be allowed to be 0, then theoriginal transformation, H, would be a constant function.
James M. Hammer, III Möbius Transformations
![Page 23: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/23.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Basic Transformations
There are four basic transformations to be aware of:
I Translation: Tb = z + b; b 2 CI Rotation: R� = e i�z ; 0 � � � 2�.I Dilation: D� = �z ; � 2 R
I Reciprocal: R =1z
Each of which can be expressed as the product of two inversions(For proof, see Theorems 2.2-2.4)
James M. Hammer, III Möbius Transformations
![Page 24: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/24.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Basic Transformations
There are four basic transformations to be aware of:
I Translation: Tb = z + b; b 2 C
I Rotation: R� = e i�z ; 0 � � � 2�.I Dilation: D� = �z ; � 2 R
I Reciprocal: R =1z
Each of which can be expressed as the product of two inversions(For proof, see Theorems 2.2-2.4)
James M. Hammer, III Möbius Transformations
![Page 25: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/25.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Basic Transformations
There are four basic transformations to be aware of:
I Translation: Tb = z + b; b 2 CI Rotation: R� = e i�z ; 0 � � � 2�.
I Dilation: D� = �z ; � 2 R
I Reciprocal: R =1z
Each of which can be expressed as the product of two inversions(For proof, see Theorems 2.2-2.4)
James M. Hammer, III Möbius Transformations
![Page 26: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/26.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Basic Transformations
There are four basic transformations to be aware of:
I Translation: Tb = z + b; b 2 CI Rotation: R� = e i�z ; 0 � � � 2�.I Dilation: D� = �z ; � 2 R
I Reciprocal: R =1z
Each of which can be expressed as the product of two inversions(For proof, see Theorems 2.2-2.4)
James M. Hammer, III Möbius Transformations
![Page 27: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/27.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Basic Transformations
There are four basic transformations to be aware of:
I Translation: Tb = z + b; b 2 CI Rotation: R� = e i�z ; 0 � � � 2�.I Dilation: D� = �z ; � 2 R
I Reciprocal: R =1z
Each of which can be expressed as the product of two inversions(For proof, see Theorems 2.2-2.4)
James M. Hammer, III Möbius Transformations
![Page 28: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/28.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Basic Transformations
There are four basic transformations to be aware of:
I Translation: Tb = z + b; b 2 CI Rotation: R� = e i�z ; 0 � � � 2�.I Dilation: D� = �z ; � 2 R
I Reciprocal: R =1z
Each of which can be expressed as the product of two inversions(For proof, see Theorems 2.2-2.4)
James M. Hammer, III Möbius Transformations
![Page 29: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/29.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Decomposing Möbius Transformations
TheoremEvery linear fractional transformation (i.e. Möbiustransformation) is a composition of translations, dilations,and inversions.
Proof.Simple algebra shows that
H =az + bcz + d
=bc � ad
c2 � 1
z +dc
+ac:
Which is clearly the composition of dilations, inversions, andtranslations (for details, see Theorem 2.5.)
James M. Hammer, III Möbius Transformations
![Page 30: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/30.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Decomposing Möbius Transformations
TheoremEvery linear fractional transformation (i.e. Möbiustransformation) is a composition of translations, dilations,and inversions.
Proof.Simple algebra shows that
H =az + bcz + d
=bc � ad
c2 � 1
z +dc
+ac:
Which is clearly the composition of dilations, inversions, andtranslations (for details, see Theorem 2.5.)
James M. Hammer, III Möbius Transformations
![Page 31: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/31.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition of Möbius TransformationsComposition of Möbius Transformations
Decomposing Möbius Transformations
TheoremEvery linear fractional transformation (i.e. Möbiustransformation) is a composition of translations, dilations,and inversions.
Proof.Simple algebra shows that
H =az + bcz + d
=bc � ad
c2 � 1
z +dc
+ac:
Which is clearly the composition of dilations, inversions, andtranslations (for details, see Theorem 2.5.)
James M. Hammer, III Möbius Transformations
![Page 32: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/32.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition
Definition of Circle Preserving
A transformation is called circle preserving if it carriesstraight lines and circles into straight lines and circles.
TheoremMöbius transformations are circle preserving.
Proof.This is quite computation intensive; so, only an outline will bepresented. Approach this as a proof by cases.
I Circles in the pre-image map into either circles or lines inthe plane.
I Lines in the pre-image map into either lines or circles inthe plane.
For details, see Theorem 3.1, Hammer 8.
James M. Hammer, III Möbius Transformations
![Page 33: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/33.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition
Definition of Circle Preserving
A transformation is called circle preserving if it carriesstraight lines and circles into straight lines and circles.
TheoremMöbius transformations are circle preserving.
Proof.This is quite computation intensive; so, only an outline will bepresented. Approach this as a proof by cases.
I Circles in the pre-image map into either circles or lines inthe plane.
I Lines in the pre-image map into either lines or circles inthe plane.
For details, see Theorem 3.1, Hammer 8.
James M. Hammer, III Möbius Transformations
![Page 34: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/34.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition
Definition of Circle Preserving
A transformation is called circle preserving if it carriesstraight lines and circles into straight lines and circles.
TheoremMöbius transformations are circle preserving.
Proof.This is quite computation intensive; so, only an outline will bepresented. Approach this as a proof by cases.
I Circles in the pre-image map into either circles or lines inthe plane.
I Lines in the pre-image map into either lines or circles inthe plane.
For details, see Theorem 3.1, Hammer 8.
James M. Hammer, III Möbius Transformations
![Page 35: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/35.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition
Definition of Circle Preserving
A transformation is called circle preserving if it carriesstraight lines and circles into straight lines and circles.
TheoremMöbius transformations are circle preserving.
Proof.This is quite computation intensive; so, only an outline will bepresented. Approach this as a proof by cases.
I Circles in the pre-image map into either circles or lines inthe plane.
I Lines in the pre-image map into either lines or circles inthe plane.
For details, see Theorem 3.1, Hammer 8.
James M. Hammer, III Möbius Transformations
![Page 36: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/36.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition
Definition of Circle Preserving
A transformation is called circle preserving if it carriesstraight lines and circles into straight lines and circles.
TheoremMöbius transformations are circle preserving.
Proof.This is quite computation intensive; so, only an outline will bepresented. Approach this as a proof by cases.
I Circles in the pre-image map into either circles or lines inthe plane.
I Lines in the pre-image map into either lines or circles inthe plane.
For details, see Theorem 3.1, Hammer 8.
James M. Hammer, III Möbius Transformations
![Page 37: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/37.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Definition
Definition of Circle Preserving
A transformation is called circle preserving if it carriesstraight lines and circles into straight lines and circles.
TheoremMöbius transformations are circle preserving.
Proof.This is quite computation intensive; so, only an outline will bepresented. Approach this as a proof by cases.
I Circles in the pre-image map into either circles or lines inthe plane.
I Lines in the pre-image map into either lines or circles inthe plane.
For details, see Theorem 3.1, Hammer 8.James M. Hammer, III Möbius Transformations
![Page 38: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/38.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Goal
It is the goal of the rest of this presentation to show thatMöbius transformations can be expressed by:
I Map the complex plane onto the unit sphere�S2� via a
stereographic projection.I A rigid transformation of the sphere.I Map the unit sphere back onto the complex plane via a
stereographic projection.
James M. Hammer, III Möbius Transformations
![Page 39: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/39.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Goal
It is the goal of the rest of this presentation to show thatMöbius transformations can be expressed by:
I Map the complex plane onto the unit sphere�S2� via a
stereographic projection.
I A rigid transformation of the sphere.I Map the unit sphere back onto the complex plane via a
stereographic projection.
James M. Hammer, III Möbius Transformations
![Page 40: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/40.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Goal
It is the goal of the rest of this presentation to show thatMöbius transformations can be expressed by:
I Map the complex plane onto the unit sphere�S2� via a
stereographic projection.I A rigid transformation of the sphere.
I Map the unit sphere back onto the complex plane via astereographic projection.
James M. Hammer, III Möbius Transformations
![Page 41: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/41.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Goal
It is the goal of the rest of this presentation to show thatMöbius transformations can be expressed by:
I Map the complex plane onto the unit sphere�S2� via a
stereographic projection.I A rigid transformation of the sphere.I Map the unit sphere back onto the complex plane via a
stereographic projection.
James M. Hammer, III Möbius Transformations
![Page 42: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/42.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
The Extended Complex Plane
The extended complex plane corresponds to the complexplane with the concept of a point at infinity added on. Thispoint at infinity will become important for completing thestereographic projection.
The extended complex plane will be denoted as C.
James M. Hammer, III Möbius Transformations
![Page 43: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/43.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
The Extended Complex Plane
The extended complex plane corresponds to the complexplane with the concept of a point at infinity added on. Thispoint at infinity will become important for completing thestereographic projection.
The extended complex plane will be denoted as C.
James M. Hammer, III Möbius Transformations
![Page 44: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/44.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Description
To produce a stereographic projection from the extendedcomplex plane to the sphere, take the following steps.
I Allow C to cut through�S2�.
I Draw a line from a point, z , in C to N , the north pole of�S2�.
I The intersection of the line drawn with the outside of thesphere is the point on
�S2� of z .
I Cover N with the point at infinity.
To use a stereographic projection from the sphere to thecomplex plane, draw the line from N to the point on thesphere. The intersection of the line and the complex plane willbe the image of the point on the sphere on the complex plane.
James M. Hammer, III Möbius Transformations
![Page 45: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/45.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Description
To produce a stereographic projection from the extendedcomplex plane to the sphere, take the following steps.
I Allow C to cut through�S2�.
I Draw a line from a point, z , in C to N , the north pole of�S2�.
I The intersection of the line drawn with the outside of thesphere is the point on
�S2� of z .
I Cover N with the point at infinity.
To use a stereographic projection from the sphere to thecomplex plane, draw the line from N to the point on thesphere. The intersection of the line and the complex plane willbe the image of the point on the sphere on the complex plane.
James M. Hammer, III Möbius Transformations
![Page 46: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/46.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Description
To produce a stereographic projection from the extendedcomplex plane to the sphere, take the following steps.
I Allow C to cut through�S2�.
I Draw a line from a point, z , in C to N , the north pole of�S2�.
I The intersection of the line drawn with the outside of thesphere is the point on
�S2� of z .
I Cover N with the point at infinity.
To use a stereographic projection from the sphere to thecomplex plane, draw the line from N to the point on thesphere. The intersection of the line and the complex plane willbe the image of the point on the sphere on the complex plane.
James M. Hammer, III Möbius Transformations
![Page 47: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/47.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Description
To produce a stereographic projection from the extendedcomplex plane to the sphere, take the following steps.
I Allow C to cut through�S2�.
I Draw a line from a point, z , in C to N , the north pole of�S2�.
I The intersection of the line drawn with the outside of thesphere is the point on
�S2� of z .
I Cover N with the point at infinity.
To use a stereographic projection from the sphere to thecomplex plane, draw the line from N to the point on thesphere. The intersection of the line and the complex plane willbe the image of the point on the sphere on the complex plane.
James M. Hammer, III Möbius Transformations
![Page 48: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/48.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Description
To produce a stereographic projection from the extendedcomplex plane to the sphere, take the following steps.
I Allow C to cut through�S2�.
I Draw a line from a point, z , in C to N , the north pole of�S2�.
I The intersection of the line drawn with the outside of thesphere is the point on
�S2� of z .
I Cover N with the point at infinity.
To use a stereographic projection from the sphere to thecomplex plane, draw the line from N to the point on thesphere. The intersection of the line and the complex plane willbe the image of the point on the sphere on the complex plane.
James M. Hammer, III Möbius Transformations
![Page 49: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/49.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Equation of the Stereographic Projection
For those who are algebraically inclined, let (�; �; �) define aCartesian coordinate system.
I From the plane to the sphere: z =� + i�1 + �
.
I From a point in space, P = (�; �; �): � + i� =2z
1 + z z, and
� =1� z z1 + z z
.
James M. Hammer, III Möbius Transformations
![Page 50: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/50.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Equation of the Stereographic Projection
For those who are algebraically inclined, let (�; �; �) define aCartesian coordinate system.
I From the plane to the sphere: z =� + i�1 + �
.
I From a point in space, P = (�; �; �): � + i� =2z
1 + z z, and
� =1� z z1 + z z
.
James M. Hammer, III Möbius Transformations
![Page 51: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/51.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Equation of the Stereographic Projection
For those who are algebraically inclined, let (�; �; �) define aCartesian coordinate system.
I From the plane to the sphere: z =� + i�1 + �
.
I From a point in space, P = (�; �; �): � + i� =2z
1 + z z, and
� =1� z z1 + z z
.
James M. Hammer, III Möbius Transformations
![Page 52: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/52.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Circle Preserving Property
It would be extremely nice if the stereographic projectionrespected circles and lines as much as the Möbiustransformations of the complex plane do.
TheoremThe stereographic projection carries circles and lines of theplane into circles and “lines” on the sphere and conversely.
Proof.Substitute the equations for the stereographic projection
into the general equation of a circle, which isC (z ; z ) = Azz +Bz +Cz +D ; where A and D are realnumbers and C and D are complex conjugates.
For explicit details, please see Theorem 4.1, Hammer 13.
James M. Hammer, III Möbius Transformations
![Page 53: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/53.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Circle Preserving Property
It would be extremely nice if the stereographic projectionrespected circles and lines as much as the Möbiustransformations of the complex plane do.
TheoremThe stereographic projection carries circles and lines of theplane into circles and “lines” on the sphere and conversely.
Proof.Substitute the equations for the stereographic projection
into the general equation of a circle, which isC (z ; z ) = Azz +Bz +Cz +D ; where A and D are realnumbers and C and D are complex conjugates.
For explicit details, please see Theorem 4.1, Hammer 13.
James M. Hammer, III Möbius Transformations
![Page 54: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/54.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Circle Preserving Property
It would be extremely nice if the stereographic projectionrespected circles and lines as much as the Möbiustransformations of the complex plane do.
TheoremThe stereographic projection carries circles and lines of theplane into circles and “lines” on the sphere and conversely.
Proof.Substitute the equations for the stereographic projection
into the general equation of a circle, which isC (z ; z ) = Azz +Bz +Cz +D ; where A and D are realnumbers and C and D are complex conjugates.
For explicit details, please see Theorem 4.1, Hammer 13.
James M. Hammer, III Möbius Transformations
![Page 55: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/55.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Circle Preserving Property
It would be extremely nice if the stereographic projectionrespected circles and lines as much as the Möbiustransformations of the complex plane do.
TheoremThe stereographic projection carries circles and lines of theplane into circles and “lines” on the sphere and conversely.
Proof.Substitute the equations for the stereographic projection
into the general equation of a circle, which isC (z ; z ) = Azz +Bz +Cz +D ; where A and D are realnumbers and C and D are complex conjugates.
For explicit details, please see Theorem 4.1, Hammer 13.
James M. Hammer, III Möbius Transformations
![Page 56: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/56.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Rigid Motion of the Sphere
What kind of transformations respect circles and lines on thesphere as much as Möbius transformations of the complexplane?
The answer is the rigid transformations of the sphere.
I A rigid motion is a mapping where any pair of imagepoints have the same distance as the corresponding pair ofinverse image points.
I Rotations in any direction clearly preserves distancebetween two points.
I Translations will also preserve distance in this way.I Reflections of the unit sphere are also rigid motions.
James M. Hammer, III Möbius Transformations
![Page 57: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/57.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Rigid Motion of the Sphere
What kind of transformations respect circles and lines on thesphere as much as Möbius transformations of the complexplane? The answer is the rigid transformations of the sphere.
I A rigid motion is a mapping where any pair of imagepoints have the same distance as the corresponding pair ofinverse image points.
I Rotations in any direction clearly preserves distancebetween two points.
I Translations will also preserve distance in this way.I Reflections of the unit sphere are also rigid motions.
James M. Hammer, III Möbius Transformations
![Page 58: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/58.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Rigid Motion of the Sphere
What kind of transformations respect circles and lines on thesphere as much as Möbius transformations of the complexplane? The answer is the rigid transformations of the sphere.
I A rigid motion is a mapping where any pair of imagepoints have the same distance as the corresponding pair ofinverse image points.
I Rotations in any direction clearly preserves distancebetween two points.
I Translations will also preserve distance in this way.I Reflections of the unit sphere are also rigid motions.
James M. Hammer, III Möbius Transformations
![Page 59: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/59.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Rigid Motion of the Sphere
What kind of transformations respect circles and lines on thesphere as much as Möbius transformations of the complexplane? The answer is the rigid transformations of the sphere.
I A rigid motion is a mapping where any pair of imagepoints have the same distance as the corresponding pair ofinverse image points.
I Rotations in any direction clearly preserves distancebetween two points.
I Translations will also preserve distance in this way.I Reflections of the unit sphere are also rigid motions.
James M. Hammer, III Möbius Transformations
![Page 60: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/60.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Rigid Motion of the Sphere
What kind of transformations respect circles and lines on thesphere as much as Möbius transformations of the complexplane? The answer is the rigid transformations of the sphere.
I A rigid motion is a mapping where any pair of imagepoints have the same distance as the corresponding pair ofinverse image points.
I Rotations in any direction clearly preserves distancebetween two points.
I Translations will also preserve distance in this way.
I Reflections of the unit sphere are also rigid motions.
James M. Hammer, III Möbius Transformations
![Page 61: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/61.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Rigid Motion of the Sphere
What kind of transformations respect circles and lines on thesphere as much as Möbius transformations of the complexplane? The answer is the rigid transformations of the sphere.
I A rigid motion is a mapping where any pair of imagepoints have the same distance as the corresponding pair ofinverse image points.
I Rotations in any direction clearly preserves distancebetween two points.
I Translations will also preserve distance in this way.I Reflections of the unit sphere are also rigid motions.
James M. Hammer, III Möbius Transformations
![Page 62: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/62.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Fixed Points
How many different fixed points are needed to determine aunique Möbius transformation?
TheoremThree different points in the complex plane are all that isneeded to ensure that the Möbius transformation, H, isuniquely determined.
Proof.It is easier to prove an equivalent statement: A Möbiustransformation with three distinct fixed points is necessarily theidentity. For details, See Theorem 4.2, Hammer 15.
James M. Hammer, III Möbius Transformations
![Page 63: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/63.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Fixed Points
How many different fixed points are needed to determine aunique Möbius transformation?
TheoremThree different points in the complex plane are all that isneeded to ensure that the Möbius transformation, H, isuniquely determined.
Proof.It is easier to prove an equivalent statement: A Möbiustransformation with three distinct fixed points is necessarily theidentity. For details, See Theorem 4.2, Hammer 15.
James M. Hammer, III Möbius Transformations
![Page 64: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/64.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Fixed Points
How many different fixed points are needed to determine aunique Möbius transformation?
TheoremThree different points in the complex plane are all that isneeded to ensure that the Möbius transformation, H, isuniquely determined.
Proof.It is easier to prove an equivalent statement: A Möbiustransformation with three distinct fixed points is necessarily theidentity. For details, See Theorem 4.2, Hammer 15.
James M. Hammer, III Möbius Transformations
![Page 65: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/65.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Other Circle Preserving Transformations
Are there other circle preserving transformations in theextended complex plane that preserve orientations other thanMöbius transformations?
No!
TheoremEvery injective function mapping the complex plane intoitself that is circle preserving is either a Möbiustransformation or an anti-homography
James M. Hammer, III Möbius Transformations
![Page 66: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/66.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Other Circle Preserving Transformations
Are there other circle preserving transformations in theextended complex plane that preserve orientations other thanMöbius transformations? No!
TheoremEvery injective function mapping the complex plane intoitself that is circle preserving is either a Möbiustransformation or an anti-homography
James M. Hammer, III Möbius Transformations
![Page 67: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/67.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Other Circle Preserving Transformations
Are there other circle preserving transformations in theextended complex plane that preserve orientations other thanMöbius transformations? No!
TheoremEvery injective function mapping the complex plane intoitself that is circle preserving is either a Möbiustransformation or an anti-homography
James M. Hammer, III Möbius Transformations
![Page 68: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/68.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Other Circle Preserving Transformations
Are there other circle preserving transformations in theextended complex plane that preserve orientations other thanMöbius transformations? No!
TheoremEvery injective function mapping the complex plane intoitself that is circle preserving is either a Möbiustransformation or an anti-homography
James M. Hammer, III Möbius Transformations
![Page 69: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/69.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Proof.Define g : C ! C as H � f or H � f , such that Im (g (i)) � 0.
ShowI g is additive (i.e. g (z1 + z2) = g (z1) + g (z2)
I g (z ) = z , the identity on RI g (z ) = z , the identity on iRI g (z ) = z
This means that either f (z ) = H�1 (z ), in which case, f is aMöbius transformation or f (z ) = H�1 (z ), meaning that f is ananti-homography (i.e. either a reflection followed by a Möbiustransformation or vice versa.)
For more detail, See Theorem 4.3.
James M. Hammer, III Möbius Transformations
![Page 70: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/70.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Proof.Define g : C ! C as H � f or H � f , such that Im (g (i)) � 0.Show
I g is additive (i.e. g (z1 + z2) = g (z1) + g (z2)
I g (z ) = z , the identity on RI g (z ) = z , the identity on iRI g (z ) = z
This means that either f (z ) = H�1 (z ), in which case, f is aMöbius transformation or f (z ) = H�1 (z ), meaning that f is ananti-homography (i.e. either a reflection followed by a Möbiustransformation or vice versa.)
For more detail, See Theorem 4.3.
James M. Hammer, III Möbius Transformations
![Page 71: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/71.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Proof.Define g : C ! C as H � f or H � f , such that Im (g (i)) � 0.Show
I g is additive (i.e. g (z1 + z2) = g (z1) + g (z2)
I g (z ) = z , the identity on R
I g (z ) = z , the identity on iRI g (z ) = z
This means that either f (z ) = H�1 (z ), in which case, f is aMöbius transformation or f (z ) = H�1 (z ), meaning that f is ananti-homography (i.e. either a reflection followed by a Möbiustransformation or vice versa.)
For more detail, See Theorem 4.3.
James M. Hammer, III Möbius Transformations
![Page 72: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/72.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Proof.Define g : C ! C as H � f or H � f , such that Im (g (i)) � 0.Show
I g is additive (i.e. g (z1 + z2) = g (z1) + g (z2)
I g (z ) = z , the identity on RI g (z ) = z , the identity on iR
I g (z ) = zThis means that either f (z ) = H�1 (z ), in which case, f is aMöbius transformation or f (z ) = H�1 (z ), meaning that f is ananti-homography (i.e. either a reflection followed by a Möbiustransformation or vice versa.)
For more detail, See Theorem 4.3.
James M. Hammer, III Möbius Transformations
![Page 73: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/73.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Proof.Define g : C ! C as H � f or H � f , such that Im (g (i)) � 0.Show
I g is additive (i.e. g (z1 + z2) = g (z1) + g (z2)
I g (z ) = z , the identity on RI g (z ) = z , the identity on iRI g (z ) = z
This means that either f (z ) = H�1 (z ), in which case, f is aMöbius transformation or f (z ) = H�1 (z ), meaning that f is ananti-homography (i.e. either a reflection followed by a Möbiustransformation or vice versa.)
For more detail, See Theorem 4.3.
James M. Hammer, III Möbius Transformations
![Page 74: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/74.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Proof.Define g : C ! C as H � f or H � f , such that Im (g (i)) � 0.Show
I g is additive (i.e. g (z1 + z2) = g (z1) + g (z2)
I g (z ) = z , the identity on RI g (z ) = z , the identity on iRI g (z ) = z
This means that either f (z ) = H�1 (z ), in which case, f is aMöbius transformation
or f (z ) = H�1 (z ), meaning that f is ananti-homography (i.e. either a reflection followed by a Möbiustransformation or vice versa.)
For more detail, See Theorem 4.3.
James M. Hammer, III Möbius Transformations
![Page 75: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/75.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Proof.Define g : C ! C as H � f or H � f , such that Im (g (i)) � 0.Show
I g is additive (i.e. g (z1 + z2) = g (z1) + g (z2)
I g (z ) = z , the identity on RI g (z ) = z , the identity on iRI g (z ) = z
This means that either f (z ) = H�1 (z ), in which case, f is aMöbius transformation or f (z ) = H�1 (z ), meaning that f is ananti-homography (i.e. either a reflection followed by a Möbiustransformation or vice versa.)
For more detail, See Theorem 4.3.
James M. Hammer, III Möbius Transformations
![Page 76: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/76.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Proof.Define g : C ! C as H � f or H � f , such that Im (g (i)) � 0.Show
I g is additive (i.e. g (z1 + z2) = g (z1) + g (z2)
I g (z ) = z , the identity on RI g (z ) = z , the identity on iRI g (z ) = z
This means that either f (z ) = H�1 (z ), in which case, f is aMöbius transformation or f (z ) = H�1 (z ), meaning that f is ananti-homography (i.e. either a reflection followed by a Möbiustransformation or vice versa.)
For more detail, See Theorem 4.3.
James M. Hammer, III Möbius Transformations
![Page 77: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/77.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
CorollaryEvery circle preserving transformation of the completedplane, which preserves the sense of rotation (orientation) atone point, is necessarily a Möbius transformation
Proof.See Corollary 4.4
James M. Hammer, III Möbius Transformations
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OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
CorollaryEvery circle preserving transformation of the completedplane, which preserves the sense of rotation (orientation) atone point, is necessarily a Möbius transformation
Proof.See Corollary 4.4
James M. Hammer, III Möbius Transformations
![Page 79: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/79.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Möbius Transformations and The Sphere
CorollaryA rigid motion of the sphere that does not changeorientation corresponds to a Möbius transformation in theextended complex plane.
Proof.See Corollary 4.4
James M. Hammer, III Möbius Transformations
![Page 80: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/80.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Möbius Transformations and The Sphere
CorollaryA rigid motion of the sphere that does not changeorientation corresponds to a Möbius transformation in theextended complex plane.
Proof.See Corollary 4.4
James M. Hammer, III Möbius Transformations
![Page 81: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/81.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Changing Orientation
CorollaryA rigid transformation of the sphere that changesorientation corresponds to an anti-homography (i.e. areflection followed by a Möbius transformation) in theextended complex plane.
Proof.See Corollary 4.6
James M. Hammer, III Möbius Transformations
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OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Stereographic ProjectionRigid Motion of the SphereClassification of Möbius TransformationsRelation to the Sphere
Changing Orientation
CorollaryA rigid transformation of the sphere that changesorientation corresponds to an anti-homography (i.e. areflection followed by a Möbius transformation) in theextended complex plane.
Proof.See Corollary 4.6
James M. Hammer, III Möbius Transformations
![Page 83: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/83.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Wrap-up
In Summary, The following topics have been fleshed out:I General information on the Complex Plane.
I Definition of Möbius transformations.I What a Möbius transformation is composed of.I The circle preserving property of Möbius transformations
and the rigid motions of the sphere.I The relationship between the Möbius transformations of
the complex plane and the unit sphere.
Thank you for your time and generous attention.Any Questions?
James M. Hammer, III Möbius Transformations
![Page 84: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/84.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Wrap-up
In Summary, The following topics have been fleshed out:I General information on the Complex Plane.I Definition of Möbius transformations.
I What a Möbius transformation is composed of.I The circle preserving property of Möbius transformations
and the rigid motions of the sphere.I The relationship between the Möbius transformations of
the complex plane and the unit sphere.
Thank you for your time and generous attention.Any Questions?
James M. Hammer, III Möbius Transformations
![Page 85: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/85.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Wrap-up
In Summary, The following topics have been fleshed out:I General information on the Complex Plane.I Definition of Möbius transformations.I What a Möbius transformation is composed of.
I The circle preserving property of Möbius transformationsand the rigid motions of the sphere.
I The relationship between the Möbius transformations ofthe complex plane and the unit sphere.
Thank you for your time and generous attention.Any Questions?
James M. Hammer, III Möbius Transformations
![Page 86: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/86.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Wrap-up
In Summary, The following topics have been fleshed out:I General information on the Complex Plane.I Definition of Möbius transformations.I What a Möbius transformation is composed of.I The circle preserving property of Möbius transformations
and the rigid motions of the sphere.
I The relationship between the Möbius transformations ofthe complex plane and the unit sphere.
Thank you for your time and generous attention.Any Questions?
James M. Hammer, III Möbius Transformations
![Page 87: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/87.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Wrap-up
In Summary, The following topics have been fleshed out:I General information on the Complex Plane.I Definition of Möbius transformations.I What a Möbius transformation is composed of.I The circle preserving property of Möbius transformations
and the rigid motions of the sphere.I The relationship between the Möbius transformations of
the complex plane and the unit sphere.
Thank you for your time and generous attention.Any Questions?
James M. Hammer, III Möbius Transformations
![Page 88: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/88.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Wrap-up
In Summary, The following topics have been fleshed out:I General information on the Complex Plane.I Definition of Möbius transformations.I What a Möbius transformation is composed of.I The circle preserving property of Möbius transformations
and the rigid motions of the sphere.I The relationship between the Möbius transformations of
the complex plane and the unit sphere.
Thank you for your time and generous attention.
Any Questions?
James M. Hammer, III Möbius Transformations
![Page 89: Möbius Transformations - Cedar Crest College · I Möbius transformations are defined over the Complex plane (denoted C.) I Algebraically, the equation, x2 = 1 should have a solution](https://reader033.vdocument.in/reader033/viewer/2022042121/5e9b5f639ca0b3673e5653c1/html5/thumbnails/89.jpg)
OutlineIntroduction
Cardinal FormsCircle Preserving Property
Relationship to SphereConclusion
Wrap-up
In Summary, The following topics have been fleshed out:I General information on the Complex Plane.I Definition of Möbius transformations.I What a Möbius transformation is composed of.I The circle preserving property of Möbius transformations
and the rigid motions of the sphere.I The relationship between the Möbius transformations of
the complex plane and the unit sphere.
Thank you for your time and generous attention.Any Questions?
James M. Hammer, III Möbius Transformations