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An Introduction toSymplectic and Contact Topology

and theTechnique of Generating Families

Lisa Traynor

Bryn Mawr College

March 2014

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 1 / 40

Outline

1 Introduction to Symplectic and Contact Topology

2 Introduction to Generating Families

3 Invariants from Generating FamiliesGenerating Family Homology for a Legendrian SubmanifoldWrapped Generating Family Cohomology for a LagrangianCobordism

Outline

1 Introduction to Symplectic and Contact Topology

2 Introduction to Generating Families

3 Invariants from Generating FamiliesGenerating Family Homology for a Legendrian SubmanifoldWrapped Generating Family Cohomology for a LagrangianCobordism

Outline

1 Introduction to Symplectic and Contact Topology

2 Introduction to Generating Families

3 Invariants from Generating FamiliesGenerating Family Homology for a Legendrian SubmanifoldWrapped Generating Family Cohomology for a LagrangianCobordism

Where Are We?

1 Introduction to Symplectic and Contact Topology

2 Introduction to Generating Families

3 Invariants from Generating FamiliesGenerating Family Homology for a Legendrian SubmanifoldWrapped Generating Family Cohomology for a LagrangianCobordism

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 3 / 40

Important Symplectic and Contact Objects

x

y

zy

x

Symplectic Manifold (X 2n,!)

Symplectomorphism ⇤! = !

Lagrangian SubmanifoldLn : !|TL ⌘ 0

Contact Manifold (Y 2n+1, ⇠)

Contactomorphism⇤⇠ = ⇠

Legendrian Submanifold⇤n : T⇤ ⇢ ⇠

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 4 / 40

Symplectic Manifolds:�

X 2n,!�

! is a closed, non-degenerate 2-form:

d! = 0, !n is a volume form.

Example

Any orientable surface ⌃ with area form !;�

R2n,!0 = dx1 ^ dy1 + · · ·+ dxn ^ dyn�

;Cotangent Bundle, T ⇤M, has a canonical 1-form �0,!0 = d�0 is a symplectic form.

! S4 is not a symplectic manifold: H2(S4) = 0.

Theorem (Darboux’s Theorem)All symplectic manifolds are locally equivalent to

R2n,!0�

.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 5 / 40

Symplectic Manifolds:�

X 2n,!�

! is a closed, non-degenerate 2-form:

d! = 0, !n is a volume form.

ExampleAny orientable surface ⌃ with area form !;

R2n,!0 = dx1 ^ dy1 + · · ·+ dxn ^ dyn�

;Cotangent Bundle, T ⇤M, has a canonical 1-form �0,!0 = d�0 is a symplectic form.

! S4 is not a symplectic manifold: H2(S4) = 0.

Theorem (Darboux’s Theorem)All symplectic manifolds are locally equivalent to

R2n,!0�

.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 5 / 40

Symplectic Manifolds:�

X 2n,!�

! is a closed, non-degenerate 2-form:

d! = 0, !n is a volume form.

ExampleAny orientable surface ⌃ with area form !;�

R2n,!0 = dx1 ^ dy1 + · · ·+ dxn ^ dyn�

;

Cotangent Bundle, T ⇤M, has a canonical 1-form �0,!0 = d�0 is a symplectic form.

! S4 is not a symplectic manifold: H2(S4) = 0.

Theorem (Darboux’s Theorem)All symplectic manifolds are locally equivalent to

R2n,!0�

.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 5 / 40

Symplectic Manifolds:�

X 2n,!�

! is a closed, non-degenerate 2-form:

d! = 0, !n is a volume form.

ExampleAny orientable surface ⌃ with area form !;�

R2n,!0 = dx1 ^ dy1 + · · ·+ dxn ^ dyn�

;Cotangent Bundle, T ⇤M, has a canonical 1-form �0,!0 = d�0 is a symplectic form.

! S4 is not a symplectic manifold: H2(S4) = 0.

Theorem (Darboux’s Theorem)All symplectic manifolds are locally equivalent to

R2n,!0�

.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 5 / 40

Symplectic Manifolds:�

X 2n,!�

! is a closed, non-degenerate 2-form:

d! = 0, !n is a volume form.

ExampleAny orientable surface ⌃ with area form !;�

R2n,!0 = dx1 ^ dy1 + · · ·+ dxn ^ dyn�

;Cotangent Bundle, T ⇤M, has a canonical 1-form �0,!0 = d�0 is a symplectic form.

! S4 is not a symplectic manifold: H2(S4) = 0.

Theorem (Darboux’s Theorem)All symplectic manifolds are locally equivalent to

R2n,!0�

.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 5 / 40

Symplectic Manifolds:�

X 2n,!�

! is a closed, non-degenerate 2-form:

d! = 0, !n is a volume form.

ExampleAny orientable surface ⌃ with area form !;�

R2n,!0 = dx1 ^ dy1 + · · ·+ dxn ^ dyn�

;Cotangent Bundle, T ⇤M, has a canonical 1-form �0,!0 = d�0 is a symplectic form.

! S4 is not a symplectic manifold: H2(S4) = 0.

Theorem (Darboux’s Theorem)All symplectic manifolds are locally equivalent to

R2n,!0�

.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 5 / 40

Symplectic Diffeomorphisms: !(v ,w) = !( ⇤v , ⇤w).

Example

(⌃2,!): Any area-preserving transformation;

(R2n,!0): Products of area-preserving transformations of thexiyi -planes;

(X 2n,!): Hamiltonian Functions and Vector FieldsFor any smooth Ht : X ! R, define vt by

!(vt , ·) = dHt ;

The flow of vt defines a symplectic isotopy t : (X ,!) ! (X ,!).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 6 / 40

Symplectic Diffeomorphisms: !(v ,w) = !( ⇤v , ⇤w).

Example(⌃2,!): Any area-preserving transformation;

(R2n,!0): Products of area-preserving transformations of thexiyi -planes;

(X 2n,!): Hamiltonian Functions and Vector FieldsFor any smooth Ht : X ! R, define vt by

!(vt , ·) = dHt ;

The flow of vt defines a symplectic isotopy t : (X ,!) ! (X ,!).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 6 / 40

Symplectic Diffeomorphisms: !(v ,w) = !( ⇤v , ⇤w).

Example(⌃2,!): Any area-preserving transformation;

(R2n,!0): Products of area-preserving transformations of thexiyi -planes;

(X 2n,!): Hamiltonian Functions and Vector FieldsFor any smooth Ht : X ! R, define vt by

!(vt , ·) = dHt ;

The flow of vt defines a symplectic isotopy t : (X ,!) ! (X ,!).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 6 / 40

Symplectic Diffeomorphisms: !(v ,w) = !( ⇤v , ⇤w).

Example(⌃2,!): Any area-preserving transformation;

(R2n,!0): Products of area-preserving transformations of thexiyi -planes;

(X 2n,!): Hamiltonian Functions and Vector FieldsFor any smooth Ht : X ! R, define vt by

!(vt , ·) = dHt ;

The flow of vt defines a symplectic isotopy t : (X ,!) ! (X ,!).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 6 / 40

Lagrangian Submanifolds: Ln : !|TL ⌘ 0

Example

(⌃2,!): Any embedded curve is Lagrangian;

(R2n,!0): The x1x2x3 . . . xn-plane is Lagrangianthe x1y1x3 . . . xn-plane is not Lagrangian;

(T ⇤M, d�0): For any function f : M ! R,the section �df ⇢ T ⇤M is a Lagrangian submanifold.

! There is no embedded Lagrangian S2 in R4.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 7 / 40

Lagrangian Submanifolds: Ln : !|TL ⌘ 0

Example(⌃2,!): Any embedded curve is Lagrangian;

(R2n,!0): The x1x2x3 . . . xn-plane is Lagrangianthe x1y1x3 . . . xn-plane is not Lagrangian;

(T ⇤M, d�0): For any function f : M ! R,the section �df ⇢ T ⇤M is a Lagrangian submanifold.

! There is no embedded Lagrangian S2 in R4.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 7 / 40

Lagrangian Submanifolds: Ln : !|TL ⌘ 0

Example(⌃2,!): Any embedded curve is Lagrangian;

(R2n,!0): The x1x2x3 . . . xn-plane is Lagrangianthe x1y1x3 . . . xn-plane is not Lagrangian;

(T ⇤M, d�0): For any function f : M ! R,the section �df ⇢ T ⇤M is a Lagrangian submanifold.

! There is no embedded Lagrangian S2 in R4.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 7 / 40

Lagrangian Submanifolds: Ln : !|TL ⌘ 0

Example(⌃2,!): Any embedded curve is Lagrangian;

(R2n,!0): The x1x2x3 . . . xn-plane is Lagrangianthe x1y1x3 . . . xn-plane is not Lagrangian;

(T ⇤M, d�0): For any function f : M ! R,the section �df ⇢ T ⇤M is a Lagrangian submanifold.

! There is no embedded Lagrangian S2 in R4.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 7 / 40

Lagrangian Submanifolds: Ln : !|TL ⌘ 0

Example(⌃2,!): Any embedded curve is Lagrangian;

(R2n,!0): The x1x2x3 . . . xn-plane is Lagrangianthe x1y1x3 . . . xn-plane is not Lagrangian;

(T ⇤M, d�0): For any function f : M ! R,the section �df ⇢ T ⇤M is a Lagrangian submanifold.

! There is no embedded Lagrangian S2 in R4.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 7 / 40

Contact Manifolds: (Y 2n+1, ⇠)

⇠ is a field of maximally non-integrable tangent hyperplanes:

⇠ = ker↵ =) ↵ ^ (d↵)n 6= 0.

Example

R3, ⇠0 = ker(dz � ydx)�

;�

R2n+1, ⇠0 = ker(dz �P

yidxi)�

;(1-Jet Bundles) J1M = T ⇤M ⇥ R has a canonical ⇠0;[Lutz-Martinet] On any closed, orientable 3-manifold, every2-plane field is homotopic to a contact structure.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 8 / 40

Contact Manifolds: (Y 2n+1, ⇠)

⇠ is a field of maximally non-integrable tangent hyperplanes:

⇠ = ker↵ =) ↵ ^ (d↵)n 6= 0.

Example�

R3, ⇠0 = ker(dz � ydx)�

;

R2n+1, ⇠0 = ker(dz �P

yidxi)�

;(1-Jet Bundles) J1M = T ⇤M ⇥ R has a canonical ⇠0;[Lutz-Martinet] On any closed, orientable 3-manifold, every2-plane field is homotopic to a contact structure.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 8 / 40

Contact Manifolds: (Y 2n+1, ⇠)

⇠ is a field of maximally non-integrable tangent hyperplanes:

⇠ = ker↵ =) ↵ ^ (d↵)n 6= 0.

Example�

R3, ⇠0 = ker(dz � ydx)�

;�

R2n+1, ⇠0 = ker(dz �P

yidxi)�

;

(1-Jet Bundles) J1M = T ⇤M ⇥ R has a canonical ⇠0;[Lutz-Martinet] On any closed, orientable 3-manifold, every2-plane field is homotopic to a contact structure.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 8 / 40

Contact Manifolds: (Y 2n+1, ⇠)

⇠ is a field of maximally non-integrable tangent hyperplanes:

⇠ = ker↵ =) ↵ ^ (d↵)n 6= 0.

Example�

R3, ⇠0 = ker(dz � ydx)�

;�

R2n+1, ⇠0 = ker(dz �P

yidxi)�

;(1-Jet Bundles) J1M = T ⇤M ⇥ R has a canonical ⇠0;

[Lutz-Martinet] On any closed, orientable 3-manifold, every2-plane field is homotopic to a contact structure.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 8 / 40

Contact Manifolds: (Y 2n+1, ⇠)

⇠ is a field of maximally non-integrable tangent hyperplanes:

⇠ = ker↵ =) ↵ ^ (d↵)n 6= 0.

Example�

R3, ⇠0 = ker(dz � ydx)�

;�

R2n+1, ⇠0 = ker(dz �P

yidxi)�

;(1-Jet Bundles) J1M = T ⇤M ⇥ R has a canonical ⇠0;[Lutz-Martinet] On any closed, orientable 3-manifold, every2-plane field is homotopic to a contact structure.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 8 / 40

Local and Global Equivalence of Contact Structures

Theorem (Darboux’s Theorem)All contact manifolds are locally equivalent to

R2n+1, ⇠0�

.

Important Problem: Understand the different contact structureson a fixed smooth manifold.

⇠0, ⇠1 : ⇠0 and ⇠1 are homotopic as plane fields,6 9' : (Y , ⇠0) ! (Y , ⇠1).

Theorem (Gray Stability)If ⇠t is a smooth family of contact structures on a closed manifold Y ,then there is an isotopy t : (Y , ⇠0) ! (Y , ⇠t) with (t)⇤⇠0 = ⇠t .

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 9 / 40

Local and Global Equivalence of Contact Structures

Theorem (Darboux’s Theorem)All contact manifolds are locally equivalent to

R2n+1, ⇠0�

.

Important Problem: Understand the different contact structureson a fixed smooth manifold.

⇠0, ⇠1 : ⇠0 and ⇠1 are homotopic as plane fields,6 9' : (Y , ⇠0) ! (Y , ⇠1).

Theorem (Gray Stability)If ⇠t is a smooth family of contact structures on a closed manifold Y ,then there is an isotopy t : (Y , ⇠0) ! (Y , ⇠t) with (t)⇤⇠0 = ⇠t .

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 9 / 40

Local and Global Equivalence of Contact Structures

Theorem (Darboux’s Theorem)All contact manifolds are locally equivalent to

R2n+1, ⇠0�

.

Important Problem: Understand the different contact structureson a fixed smooth manifold.

⇠0, ⇠1 : ⇠0 and ⇠1 are homotopic as plane fields,6 9' : (Y , ⇠0) ! (Y , ⇠1).

Theorem (Gray Stability)If ⇠t is a smooth family of contact structures on a closed manifold Y ,then there is an isotopy t : (Y , ⇠0) ! (Y , ⇠t) with (t)⇤⇠0 = ⇠t .

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 9 / 40

Tight vs. Overtwisted (Y 3, ⇠)

A contact 3-manifold is overtwisted if it contains an overtwisted disk,D: interior of D is transversal to ⇠ except at 1 point; @D is tangent to ⇠.

Theorem (Eliashberg)Two overtwisted structures on Y are isotopic if they are homotopic asplane fields.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 10 / 40

Tight vs. Overtwisted (Y 3, ⇠)

A contact 3-manifold is overtwisted if it contains an overtwisted disk,D: interior of D is transversal to ⇠ except at 1 point; @D is tangent to ⇠.

Theorem (Eliashberg)Two overtwisted structures on Y are isotopic if they are homotopic asplane fields.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 10 / 40

Contact Diffeomorphisms: ⇤⇠ = ⇠

Contact Vector Field: flow preserves the contact structure

contact vector field �! contact isotopy

Example

Reeb Vector Field: If ⇠ = ker↵, the Reeb vector field R↵ definedby:

R↵ 2 ker d↵, ↵(R↵) = 1,

is a contact vector field.Contact Hamiltonian Vector Field: For any smooth H : Y ! R,there is a unique vector field KH ⇢ ⇠ = ker↵ so that

VH = HR↵ + KH

is a contact vector field.

Also: time-dependent Hamiltonian functions, Ht , and vector fields VHt

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 11 / 40

Contact Diffeomorphisms: ⇤⇠ = ⇠

Contact Vector Field: flow preserves the contact structure

contact vector field �! contact isotopy

ExampleReeb Vector Field: If ⇠ = ker↵, the Reeb vector field R↵ definedby:

R↵ 2 ker d↵, ↵(R↵) = 1,

is a contact vector field.

Contact Hamiltonian Vector Field: For any smooth H : Y ! R,there is a unique vector field KH ⇢ ⇠ = ker↵ so that

VH = HR↵ + KH

is a contact vector field.

Also: time-dependent Hamiltonian functions, Ht , and vector fields VHt

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 11 / 40

Contact Diffeomorphisms: ⇤⇠ = ⇠

Contact Vector Field: flow preserves the contact structure

contact vector field �! contact isotopy

ExampleReeb Vector Field: If ⇠ = ker↵, the Reeb vector field R↵ definedby:

R↵ 2 ker d↵, ↵(R↵) = 1,

is a contact vector field.Contact Hamiltonian Vector Field: For any smooth H : Y ! R,there is a unique vector field KH ⇢ ⇠ = ker↵ so that

VH = HR↵ + KH

is a contact vector field.

Also: time-dependent Hamiltonian functions, Ht , and vector fields VHt

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 11 / 40

Contact Diffeomorphisms: ⇤⇠ = ⇠

Contact Vector Field: flow preserves the contact structure

contact vector field �! contact isotopy

ExampleReeb Vector Field: If ⇠ = ker↵, the Reeb vector field R↵ definedby:

R↵ 2 ker d↵, ↵(R↵) = 1,

is a contact vector field.Contact Hamiltonian Vector Field: For any smooth H : Y ! R,there is a unique vector field KH ⇢ ⇠ = ker↵ so that

VH = HR↵ + KH

is a contact vector field.

Also: time-dependent Hamiltonian functions, Ht , and vector fields VHt

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 11 / 40

Legendrian Submanifolds: T⇤n ⇢ ⇠

Legendrians are abundant!

Any knot/link in R3 has a Legendrian representation;

In higher dimensions, any closed sphere, torus, or n-manifold thatsatisfies certain homotopy-theoretic conditions can beC0-approximated by a Legendrian.

Interested in the classification of Legendrians up to Legendrian isotopy(equivalently, up to ambient contact isotopy).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 12 / 40

Legendrian Submanifolds: T⇤n ⇢ ⇠

Legendrians are abundant!

Any knot/link in R3 has a Legendrian representation;

In higher dimensions, any closed sphere, torus, or n-manifold thatsatisfies certain homotopy-theoretic conditions can beC0-approximated by a Legendrian.

Interested in the classification of Legendrians up to Legendrian isotopy(equivalently, up to ambient contact isotopy).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 12 / 40

Legendrian Submanifolds: T⇤n ⇢ ⇠

Legendrians are abundant!

Any knot/link in R3 has a Legendrian representation;

In higher dimensions, any closed sphere, torus, or n-manifold thatsatisfies certain homotopy-theoretic conditions can beC0-approximated by a Legendrian.

Interested in the classification of Legendrians up to Legendrian isotopy(equivalently, up to ambient contact isotopy).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 12 / 40

Legendrian Submanifolds: T⇤n ⇢ ⇠

Legendrians are abundant!

Any knot/link in R3 has a Legendrian representation;

In higher dimensions, any closed sphere, torus, or n-manifold thatsatisfies certain homotopy-theoretic conditions can beC0-approximated by a Legendrian.

Interested in the classification of Legendrians up to Legendrian isotopy(equivalently, up to ambient contact isotopy).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 12 / 40

Basic Examples of Legendrian Curves

R3, ker(dz � ydx)�

, ⇤f = Legendrian lift of the graph of f : R ! R.!"#"$%&'

("#")$

)&%&'"

*!

&("#"+

("#",-("#".

⇤f =

⇢✓

x ,dfdx

(x), f (x)◆�

⇢ R3.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 13 / 40

Basic Examples of Legendrian Curves

R3, ker(dz � ydx)�

, ⇤f = Legendrian lift of the graph of f : R ! R.!"#"$%&'

("#")$

)&%&'"

*!

&("#"+

("#",-("#". (

⇤f =

⇢✓

x ,dfdx

(x), f (x)◆�

⇢ R3.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 13 / 40

More Complicated Legendrian Shapes

⇤ = lift of the graph of this “multi-valued" function to R3

No vertical tangents allowed;

Lift is smooth (semi-cubical cusps);

At crossing, branch with lesser slope is on top.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 14 / 40

More Complicated Legendrian Shapes

⇤ = lift of the graph of this “multi-valued" function to R3

No vertical tangents allowed;

Lift is smooth (semi-cubical cusps);

At crossing, branch with lesser slope is on top.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 14 / 40

More Complicated Legendrian Shapes

⇤ = lift of the graph of this “multi-valued" function to R3

No vertical tangents allowed;

Lift is smooth (semi-cubical cusps);

At crossing, branch with lesser slope is on top.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 14 / 40

More Complicated Legendrian Shapes

⇤ = lift of the graph of this “multi-valued" function to R3

No vertical tangents allowed;

Lift is smooth (semi-cubical cusps);

At crossing, branch with lesser slope is on top.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 14 / 40

More Complicated Legendrian Shapes

⇤ = lift of the graph of this “multi-valued" function to R3

No vertical tangents allowed;

Lift is smooth (semi-cubical cusps);

At crossing, branch with lesser slope is on top.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 14 / 40

Legendrian Knots

Every topological knot/link has a Legendrian representative.

!"#"$#"%&'()*+

,*-.&'"/ 01

0!

2"%&'()*+

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 15 / 40

Legendrian Surfaces

Legendrian sphere in R5:

More possibilities for singularities:

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 16 / 40

Legendrian Surfaces

Legendrian sphere in R5:

More possibilities for singularities:

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 16 / 40

Invariants of Legendrian Submanifolds

Important Problem: Understand the equivalence ofLegendrian submanifolds

Classical Invariants: for ⇤n ⇢ R2n+1,The diffeomorphism type of ⇤;

The rotation class r(⇤) 2 [⇤,U(n)];

The Thurston-Bennequin Invariant tb(⇤) 2 Z;

( n � 4 and even) Relative invariant tb⇤(⇤1,⇤2) 2 Z/2Z.

When ⇤ = S2n, r(⇤) = 0, tb(⇤) determined from �(⇤).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 17 / 40

Invariants of Legendrian Submanifolds

Important Problem: Understand the equivalence ofLegendrian submanifolds

Classical Invariants: for ⇤n ⇢ R2n+1,

The diffeomorphism type of ⇤;

The rotation class r(⇤) 2 [⇤,U(n)];

The Thurston-Bennequin Invariant tb(⇤) 2 Z;

( n � 4 and even) Relative invariant tb⇤(⇤1,⇤2) 2 Z/2Z.

When ⇤ = S2n, r(⇤) = 0, tb(⇤) determined from �(⇤).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 17 / 40

Invariants of Legendrian Submanifolds

Important Problem: Understand the equivalence ofLegendrian submanifolds

Classical Invariants: for ⇤n ⇢ R2n+1,The diffeomorphism type of ⇤;

The rotation class r(⇤) 2 [⇤,U(n)];

The Thurston-Bennequin Invariant tb(⇤) 2 Z;

( n � 4 and even) Relative invariant tb⇤(⇤1,⇤2) 2 Z/2Z.

When ⇤ = S2n, r(⇤) = 0, tb(⇤) determined from �(⇤).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 17 / 40

Invariants of Legendrian Submanifolds

Important Problem: Understand the equivalence ofLegendrian submanifolds

Classical Invariants: for ⇤n ⇢ R2n+1,The diffeomorphism type of ⇤;

The rotation class r(⇤) 2 [⇤,U(n)];

The Thurston-Bennequin Invariant tb(⇤) 2 Z;

( n � 4 and even) Relative invariant tb⇤(⇤1,⇤2) 2 Z/2Z.

When ⇤ = S2n, r(⇤) = 0, tb(⇤) determined from �(⇤).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 17 / 40

Invariants of Legendrian Submanifolds

Important Problem: Understand the equivalence ofLegendrian submanifolds

Classical Invariants: for ⇤n ⇢ R2n+1,The diffeomorphism type of ⇤;

The rotation class r(⇤) 2 [⇤,U(n)];

The Thurston-Bennequin Invariant tb(⇤) 2 Z;

( n � 4 and even) Relative invariant tb⇤(⇤1,⇤2) 2 Z/2Z.

When ⇤ = S2n, r(⇤) = 0, tb(⇤) determined from �(⇤).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 17 / 40

Invariants of Legendrian Submanifolds

Important Problem: Understand the equivalence ofLegendrian submanifolds

Classical Invariants: for ⇤n ⇢ R2n+1,The diffeomorphism type of ⇤;

The rotation class r(⇤) 2 [⇤,U(n)];

The Thurston-Bennequin Invariant tb(⇤) 2 Z;

( n � 4 and even) Relative invariant tb⇤(⇤1,⇤2) 2 Z/2Z.

When ⇤ = S2n, r(⇤) = 0, tb(⇤) determined from �(⇤).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 17 / 40

Invariants of Legendrian Submanifolds

Important Problem: Understand the equivalence ofLegendrian submanifolds

Classical Invariants: for ⇤n ⇢ R2n+1,The diffeomorphism type of ⇤;

The rotation class r(⇤) 2 [⇤,U(n)];

The Thurston-Bennequin Invariant tb(⇤) 2 Z;

( n � 4 and even) Relative invariant tb⇤(⇤1,⇤2) 2 Z/2Z.

When ⇤ = S2n, r(⇤) = 0, tb(⇤) determined from �(⇤).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 17 / 40

Reeb Chords

Question: Is it possible to construct non-classical invariantsof Legendrian submanifolds from the Reeb chords?

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 18 / 40

Reeb Chords

Question: Is it possible to construct non-classical invariantsof Legendrian submanifolds from the Reeb chords?

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 18 / 40

Techniques to Construct Invariants from Reeb Chords

J-Holomorphic CurvesInitiated by Gromov, ’85

Applies to more general manifolds.

Generating Families of FunctionsClassic technique;

Modernized by Sikorav, Laudenbach, Chaperon, Viterbo,80’s and 90’s

Analysis is finite dimensional.Arguments apply to all dimensions.

Interesting parallels between results!Combinatorics as a bridge.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 19 / 40

Techniques to Construct Invariants from Reeb Chords

J-Holomorphic CurvesInitiated by Gromov, ’85

Applies to more general manifolds.

Generating Families of FunctionsClassic technique;

Modernized by Sikorav, Laudenbach, Chaperon, Viterbo,80’s and 90’s

Analysis is finite dimensional.Arguments apply to all dimensions.

Interesting parallels between results!Combinatorics as a bridge.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 19 / 40

Techniques to Construct Invariants from Reeb Chords

J-Holomorphic CurvesInitiated by Gromov, ’85

Applies to more general manifolds.

Generating Families of FunctionsClassic technique;

Modernized by Sikorav, Laudenbach, Chaperon, Viterbo,80’s and 90’s

Analysis is finite dimensional.Arguments apply to all dimensions.

Interesting parallels between results!

Combinatorics as a bridge.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 19 / 40

Techniques to Construct Invariants from Reeb Chords

J-Holomorphic CurvesInitiated by Gromov, ’85

Applies to more general manifolds.

Generating Families of FunctionsClassic technique;

Modernized by Sikorav, Laudenbach, Chaperon, Viterbo,80’s and 90’s

Analysis is finite dimensional.Arguments apply to all dimensions.

Interesting parallels between results!Combinatorics as a bridge.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 19 / 40

Where Are We?

1 Introduction to Symplectic and Contact Topology

2 Introduction to Generating Families

3 Invariants from Generating FamiliesGenerating Family Homology for a Legendrian SubmanifoldWrapped Generating Family Cohomology for a LagrangianCobordism

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 20 / 40

Idea of Generating Families

Manifolds of Focus:

ContactR2n+1

J1(M) = T ⇤M ⇥ R

SymplecticR2n

T ⇤(M)

In J1(M), describe Legendrian submanifolds as the “1-jet" offunctions F : M ⇥ RN ! R.

In T ⇤(M), describe Lagrangian submanifolds as the “derivatives"of functions F : M ⇥ RN ! R.

Strategy: Apply analysis/Morse theoretic arguments to these functionsto obtain invariants of the Lagrangian and Legendrian submanifolds.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 21 / 40

Idea of Generating Families

Manifolds of Focus:

ContactR2n+1

J1(M) = T ⇤M ⇥ R

SymplecticR2n

T ⇤(M)

In J1(M), describe Legendrian submanifolds as the “1-jet" offunctions F : M ⇥ RN ! R.

In T ⇤(M), describe Lagrangian submanifolds as the “derivatives"of functions F : M ⇥ RN ! R.

Strategy: Apply analysis/Morse theoretic arguments to these functionsto obtain invariants of the Lagrangian and Legendrian submanifolds.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 21 / 40

Idea of Generating Families

Manifolds of Focus:

ContactR2n+1

J1(M) = T ⇤M ⇥ R

SymplecticR2n

T ⇤(M)

In J1(M), describe Legendrian submanifolds as the “1-jet" offunctions F : M ⇥ RN ! R.

In T ⇤(M), describe Lagrangian submanifolds as the “derivatives"of functions F : M ⇥ RN ! R.

Strategy: Apply analysis/Morse theoretic arguments to these functionsto obtain invariants of the Lagrangian and Legendrian submanifolds.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 21 / 40

Idea of Generating Families

Manifolds of Focus:

ContactR2n+1

J1(M) = T ⇤M ⇥ R

SymplecticR2n

T ⇤(M)

In J1(M), describe Legendrian submanifolds as the “1-jet" offunctions F : M ⇥ RN ! R.

In T ⇤(M), describe Lagrangian submanifolds as the “derivatives"of functions F : M ⇥ RN ! R.

Strategy: Apply analysis/Morse theoretic arguments to these functionsto obtain invariants of the Lagrangian and Legendrian submanifolds.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 21 / 40

Basic Examples

R3, ker(dz � ydx)�

, ⇤f = Legendrian lift of the graph of f : R ! R.!"#"$%&'

("#")$

)&%&'"

*!

&("#"+

("#",-("#".

!"#"$%&'

("#")$

)&%&'"

*!

&("#"+

("#",-("#". (

⇤f =

⇢✓

x ,dfdx

(x), f (x)◆�

⇢ R3.

f : R ! R “generates" ⇤f .

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 22 / 40

Basic Examples

R3, ker(dz � ydx)�

, ⇤f = Legendrian lift of the graph of f : R ! R.!"#"$%&'

("#")$

)&%&'"

*!

&("#"+

("#",-("#". (

⇤f =

⇢✓

x ,dfdx

(x), f (x)◆�

⇢ R3.

f : R ! R “generates" ⇤f .

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 22 / 40

More Complicated Legendrian Shapes

⇤ = lift of the graph of this “multi-valued" function to R3 = J1R

⇤ is not the 1-jet of f : R ! R.

BUT, ⇤ can be viewed as the “1-jet" of a 1-parameter family of functions

F : R⇥ RN = {(x , e)} ! R.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 23 / 40

More Complicated Legendrian Shapes

⇤ = lift of the graph of this “multi-valued" function to R3 = J1R

⇤ is not the 1-jet of f : R ! R.

BUT, ⇤ can be viewed as the “1-jet" of a 1-parameter family of functions

F : R⇥ RN = {(x , e)} ! R.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 23 / 40

Explicit Construction

Idea: Construct a family of functions Fx : RN = {e} ! R, for x 2 R.

This family of functions “generates" ⇤.9F : R⇥ RN ! R so that

⇤ =

⇢✓

x ,@F@x

(x , e),F (x , e)◆

:@F@e

(x , e) = 0�

.

9 choices: Canchange N by stabilizing with a quadratic: eF (x , e, e) = F (x , e) +Q(e);apply a fiber-preserving diffeomorphism: eF (x , e) = F (x ,�x(e)).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 24 / 40

Explicit Construction

Idea: Construct a family of functions Fx : RN = {e} ! R, for x 2 R.

This family of functions “generates" ⇤.9F : R⇥ RN ! R so that

⇤ =

⇢✓

x ,@F@x

(x , e),F (x , e)◆

:@F@e

(x , e) = 0�

.

9 choices: Canchange N by stabilizing with a quadratic: eF (x , e, e) = F (x , e) +Q(e);apply a fiber-preserving diffeomorphism: eF (x , e) = F (x ,�x(e)).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 24 / 40

Explicit Construction

Idea: Construct a family of functions Fx : RN = {e} ! R, for x 2 R.

This family of functions “generates" ⇤.9F : R⇥ RN ! R so that

⇤ =

⇢✓

x ,@F@x

(x , e),F (x , e)◆

:@F@e

(x , e) = 0�

.

9 choices: Canchange N by stabilizing with a quadratic: eF (x , e, e) = F (x , e) +Q(e);apply a fiber-preserving diffeomorphism: eF (x , e) = F (x ,�x(e)).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 24 / 40

GF Domain has Finite Dimension

6 9F : R⇥ R1 ! R

that generates ⇤ ⇢ R3 = J1R.

But,

9F : R⇥ R2 ! R.

In general, for ⇤ ⇢ J1(M), consider F : M ⇥ RN ! R for large N.

Usually want F “nice" (quadratic or linear)outside a compact set.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 25 / 40

GF Domain has Finite Dimension

6 9F : R⇥ R1 ! R

that generates ⇤ ⇢ R3 = J1R. But,

9F : R⇥ R2 ! R.

In general, for ⇤ ⇢ J1(M), consider F : M ⇥ RN ! R for large N.

Usually want F “nice" (quadratic or linear)outside a compact set.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 25 / 40

GF Domain has Finite Dimension

6 9F : R⇥ R1 ! R

that generates ⇤ ⇢ R3 = J1R. But,

9F : R⇥ R2 ! R.

In general, for ⇤ ⇢ J1(M), consider F : M ⇥ RN ! R for large N.

Usually want F “nice" (quadratic or linear)outside a compact set.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 25 / 40

Generating Families for Lagrangian Submanifolds

Similar set up for Lagrangians:

!

"

"#$

!"#$

9F : Rn ! R so that L =��

x , @F@x (x)

: x 2 Rn .

9F : Rn ⇥ RN ! R so that L =��

x , @F@x (x , e)

: @F@e (x , e) = 0

.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 26 / 40

Generating Families for Lagrangian Submanifolds

Similar set up for Lagrangians:

!

"

"#$

!"#$

9F : Rn ! R so that L =��

x , @F@x (x)

: x 2 Rn .

!

"

"#$

!"#$

9F : Rn ⇥ RN ! R so that L =��

x , @F@x (x , e)

: @F@e (x , e) = 0

.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 26 / 40

Important Points

Not all Legendrian (Lagrangian) submanifolds have generatingfamilies.

!

"

#$%

Sabloff, Fuchs, Pushkar, and others show that for ⇤1 ⇢ R3:

9 generating family () 9 augmentation of the holomorphic-DGA.

If a Legendrian (Lagrangian) submanifold has a generating familyand t is a contact (symplectic) isotopy, then 1(⇤) has agenerating family. “Persistence / Serre Fibration"

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 27 / 40

Important Points

Not all Legendrian (Lagrangian) submanifolds have generatingfamilies.

!

"

#$%

Sabloff, Fuchs, Pushkar, and others show that for ⇤1 ⇢ R3:

9 generating family () 9 augmentation of the holomorphic-DGA.

If a Legendrian (Lagrangian) submanifold has a generating familyand t is a contact (symplectic) isotopy, then 1(⇤) has agenerating family. “Persistence / Serre Fibration"

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 27 / 40

Where Are We?

1 Introduction to Symplectic and Contact Topology

2 Introduction to Generating Families

3 Invariants from Generating FamiliesGenerating Family Homology for a Legendrian SubmanifoldWrapped Generating Family Cohomology for a LagrangianCobordism

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 28 / 40

Difference Functions of Generating Families

Given a generating family f : M ⇥ RN ! R for ⇤ ⇢ J1M,define the difference function � : M ⇥ RN ⇥ RN ! R by:

�(x , e, e) = f (x , e)� f (x , e).

Critical points of � are of two types:For each Reeb chord of ⇤, there are two critical points of � withcritical values ± (Reeb chord length);There is a non-degenerate critical submanifold diffeomorphic to ⇤with critical value 0.

As Legendrian ⇤ is isotoped, critical values born/die/change.

Apply Morse-theoretic constructions to get an invariant of ⇤ from �.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 29 / 40

Difference Functions of Generating Families

Given a generating family f : M ⇥ RN ! R for ⇤ ⇢ J1M,define the difference function � : M ⇥ RN ⇥ RN ! R by:

�(x , e, e) = f (x , e)� f (x , e).

Critical points of � are of two types:

For each Reeb chord of ⇤, there are two critical points of � withcritical values ± (Reeb chord length);There is a non-degenerate critical submanifold diffeomorphic to ⇤with critical value 0.

As Legendrian ⇤ is isotoped, critical values born/die/change.

Apply Morse-theoretic constructions to get an invariant of ⇤ from �.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 29 / 40

Difference Functions of Generating Families

Given a generating family f : M ⇥ RN ! R for ⇤ ⇢ J1M,define the difference function � : M ⇥ RN ⇥ RN ! R by:

�(x , e, e) = f (x , e)� f (x , e).

Critical points of � are of two types:For each Reeb chord of ⇤, there are two critical points of � withcritical values ± (Reeb chord length);

There is a non-degenerate critical submanifold diffeomorphic to ⇤with critical value 0.

As Legendrian ⇤ is isotoped, critical values born/die/change.

Apply Morse-theoretic constructions to get an invariant of ⇤ from �.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 29 / 40

Difference Functions of Generating Families

Given a generating family f : M ⇥ RN ! R for ⇤ ⇢ J1M,define the difference function � : M ⇥ RN ⇥ RN ! R by:

�(x , e, e) = f (x , e)� f (x , e).

Critical points of � are of two types:For each Reeb chord of ⇤, there are two critical points of � withcritical values ± (Reeb chord length);There is a non-degenerate critical submanifold diffeomorphic to ⇤with critical value 0.

As Legendrian ⇤ is isotoped, critical values born/die/change.

Apply Morse-theoretic constructions to get an invariant of ⇤ from �.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 29 / 40

Difference Functions of Generating Families

Given a generating family f : M ⇥ RN ! R for ⇤ ⇢ J1M,define the difference function � : M ⇥ RN ⇥ RN ! R by:

�(x , e, e) = f (x , e)� f (x , e).

Critical points of � are of two types:For each Reeb chord of ⇤, there are two critical points of � withcritical values ± (Reeb chord length);There is a non-degenerate critical submanifold diffeomorphic to ⇤with critical value 0.

As Legendrian ⇤ is isotoped, critical values born/die/change.

Apply Morse-theoretic constructions to get an invariant of ⇤ from �.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 29 / 40

Generating Family Homology and Cohomology

For ! � 0, H⇤(�!, ��!) = 0, for all ⇤.

Choose ✏ sufficiently small:

Definition (LT, Fuchs-Rutherford, Sabloff-LT)

GHk (f ) = Hk+N+1(�!, �✏), gGHk (f ) = Hk+N+1(�

!, ��✏),

GHk (f ) = Hk+N+1(�!, �✏), ]GHk (f ) = Hk+N+1(�!, ��✏).

Theorem (LT, Fuchs-Rutherford){GH⇤(f ) : f generates ⇤} is an invariant of ⇤.

{GH⇤(f )},n

gGH⇤(f )o

,n

]GH⇤(f )o

are also invariants of ⇤.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 30 / 40

Generating Family Homology and Cohomology

For ! � 0, H⇤(�!, ��!) = 0, for all ⇤.

Choose ✏ sufficiently small:

Definition (LT, Fuchs-Rutherford, Sabloff-LT)

GHk (f ) = Hk+N+1(�!, �✏), gGHk (f ) = Hk+N+1(�

!, ��✏),

GHk (f ) = Hk+N+1(�!, �✏), ]GHk (f ) = Hk+N+1(�!, ��✏).

Theorem (LT, Fuchs-Rutherford){GH⇤(f ) : f generates ⇤} is an invariant of ⇤.

{GH⇤(f )},n

gGH⇤(f )o

,n

]GH⇤(f )o

are also invariants of ⇤.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 30 / 40

Generating Family Homology and Cohomology

For ! � 0, H⇤(�!, ��!) = 0, for all ⇤.

Choose ✏ sufficiently small:

Definition (LT, Fuchs-Rutherford, Sabloff-LT)

GHk (f ) = Hk+N+1(�!, �✏), gGHk (f ) = Hk+N+1(�

!, ��✏),

GHk (f ) = Hk+N+1(�!, �✏), ]GHk (f ) = Hk+N+1(�!, ��✏).

Theorem (LT, Fuchs-Rutherford){GH⇤(f ) : f generates ⇤} is an invariant of ⇤.

{GH⇤(f )},n

gGH⇤(f )o

,n

]GH⇤(f )o

are also invariants of ⇤.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 30 / 40

Generating Family Homology and Cohomology

For ! � 0, H⇤(�!, ��!) = 0, for all ⇤.

Choose ✏ sufficiently small:

Definition (LT, Fuchs-Rutherford, Sabloff-LT)

GHk (f ) = Hk+N+1(�!, �✏), gGHk (f ) = Hk+N+1(�

!, ��✏),

GHk (f ) = Hk+N+1(�!, �✏), ]GHk (f ) = Hk+N+1(�!, ��✏).

Theorem (LT, Fuchs-Rutherford){GH⇤(f ) : f generates ⇤} is an invariant of ⇤.

{GH⇤(f )},n

gGH⇤(f )o

,n

]GH⇤(f )o

are also invariants of ⇤.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 30 / 40

Generating Family Polynomials

Work over a field F and encode GH⇤(f ) by its Poincaré polynomial:

�f (t) =X

i

dim GHi(f )t i

ExampleThere are two different Legendrian m(52) knots with the same tb and rvalues:

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 31 / 40

Generating Family Polynomials

Work over a field F and encode GH⇤(f ) by its Poincaré polynomial:

�f (t) =X

i

dim GHi(f )t i

ExampleThere are two different Legendrian m(52) knots with the same tb and rvalues:

!

P = t + t + t-2 2}{

P = {2+ t}

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 31 / 40

Duality for Generating Family Homology

There is a structure to the gf-polynomials:

t + 4t2, 4t�2 + 4t2

cannot occur as gf-polynomials for ⇤1 ⇢ R3.

Duality Theorem:

Theorem (Sabloff-LT)There is a long exact sequence:

· · · ! GHk�1(f ) ! GHn�k (f ) ! Hk (⇤) ! · · ·

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 32 / 40

Duality for Generating Family Homology

There is a structure to the gf-polynomials:

t + 4t2, 4t�2 + 4t2

cannot occur as gf-polynomials for ⇤1 ⇢ R3.

Duality Theorem:

Theorem (Sabloff-LT)There is a long exact sequence:

· · · ! GHk�1(f ) ! GHn�k (f ) ! Hk (⇤) ! · · ·

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 32 / 40

Open Problems for GF-Homology

Important Directions:Combinatorially calculate GF-Homology;

Construct GF-DGA.

[Henry and Rutherford] A combinatorial-DGA for Legendrian knotsmotivated by generating families

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 33 / 40

Open Problems for GF-Homology

Important Directions:Combinatorially calculate GF-Homology;

Construct GF-DGA.

[Henry and Rutherford] A combinatorial-DGA for Legendrian knotsmotivated by generating families

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 33 / 40

Lagrangian Cobordisms between Legendrians

⇤� �L ⇤+

denotes an exact Lagrangian cobordismthat is cylindrical over ⇤± at ±1.

R2n+1

R2n+1

!

"

#

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 34 / 40

Wrapped Cohomology for Lagrangian Cobordisms

Lagrangian Floer Cohomology: For closed Lagrangians, define acohomology with underlying cochain complex the intersection points ofthe Lagrangians.

Wrapped Floer Cohomology:[Abbondodolo-Schwarz, Fukaya-Seidel-Smith, Abouzaid-Smith]For Lagrangian cobordisms, cochain complex generated byintersection between the compact pieces of two Lagrangiancobordisms and the Reeb chords at the Legendrian ends.

How to study with generating families?

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 35 / 40

Wrapped Cohomology for Lagrangian Cobordisms

Lagrangian Floer Cohomology: For closed Lagrangians, define acohomology with underlying cochain complex the intersection points ofthe Lagrangians.

Wrapped Floer Cohomology:[Abbondodolo-Schwarz, Fukaya-Seidel-Smith, Abouzaid-Smith]For Lagrangian cobordisms, cochain complex generated byintersection between the compact pieces of two Lagrangiancobordisms and the Reeb chords at the Legendrian ends.

How to study with generating families?

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 35 / 40

Wrapped Cohomology for Lagrangian Cobordisms

Lagrangian Floer Cohomology: For closed Lagrangians, define acohomology with underlying cochain complex the intersection points ofthe Lagrangians.

Wrapped Floer Cohomology:[Abbondodolo-Schwarz, Fukaya-Seidel-Smith, Abouzaid-Smith]For Lagrangian cobordisms, cochain complex generated byintersection between the compact pieces of two Lagrangiancobordisms and the Reeb chords at the Legendrian ends.

How to study with generating families?

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 35 / 40

GF-Compatible Lagrangian Cobordisms

Assume Legendrians and Lagrangian can be described by compatiblegenerating families:

(⇤�, f�) �(L,F ) (⇤+, f+).

: R⇥ R2n+1 ! T ⇤(R+ ⇥ Rn)

L 7! (L)

9 generating families

f± : Rn ⇥ RN ! R for ⇤± (linear-at-1); andF : R+ ⇥ Rn ⇥ RN ! R for (L) ⇢ T ⇤(R+ ⇥ Rn) that correlates tof± outside a compact set of R+.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 36 / 40

GF-Compatible Lagrangian Cobordisms

Assume Legendrians and Lagrangian can be described by compatiblegenerating families:

(⇤�, f�) �(L,F ) (⇤+, f+).

: R⇥ R2n+1 ! T ⇤(R+ ⇥ Rn)

L 7! (L)

9 generating familiesf± : Rn ⇥ RN ! R for ⇤± (linear-at-1); and

F : R+ ⇥ Rn ⇥ RN ! R for (L) ⇢ T ⇤(R+ ⇥ Rn) that correlates tof± outside a compact set of R+.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 36 / 40

GF-Compatible Lagrangian Cobordisms

Assume Legendrians and Lagrangian can be described by compatiblegenerating families:

(⇤�, f�) �(L,F ) (⇤+, f+).

: R⇥ R2n+1 ! T ⇤(R+ ⇥ Rn)

L 7! (L)

9 generating familiesf± : Rn ⇥ RN ! R for ⇤± (linear-at-1); andF : R+ ⇥ Rn ⇥ RN ! R for (L) ⇢ T ⇤(R+ ⇥ Rn) that correlates tof± outside a compact set of R+.

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 36 / 40

Wrapped Generating Family Cohomology Groups

Given a generating family F : R+ ⇥ M ⇥ RN ! R for (L) ⇢ T ⇤(R+ ⇥ M), and a function H : R+ ! R,

define the sheared difference function � : M ⇥ RN ⇥ RN ! R by:

�(t , x , e, e) = F (t , x , e)� F (t , x , e) + H(t).

KEY: There is a non-degenerate critical submanifold with value 0diffeomorphic to the compact L, and non-degenerate critical pointscorresponding to the Reeb chords of ⇤±.

WGH⇤(F ) := H⇤(�1,�✏).

In fact, WGH⇤(F ) ' H⇤(L,⇤+).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 37 / 40

Wrapped Generating Family Cohomology Groups

Given a generating family F : R+ ⇥ M ⇥ RN ! R for (L) ⇢ T ⇤(R+ ⇥ M), and a function H : R+ ! R,

define the sheared difference function � : M ⇥ RN ⇥ RN ! R by:

�(t , x , e, e) = F (t , x , e)� F (t , x , e) + H(t).

KEY: There is a non-degenerate critical submanifold with value 0diffeomorphic to the compact L, and non-degenerate critical pointscorresponding to the Reeb chords of ⇤±.

WGH⇤(F ) := H⇤(�1,�✏).

In fact, WGH⇤(F ) ' H⇤(L,⇤+).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 37 / 40

Wrapped Generating Family Cohomology Groups

Given a generating family F : R+ ⇥ M ⇥ RN ! R for (L) ⇢ T ⇤(R+ ⇥ M), and a function H : R+ ! R,

define the sheared difference function � : M ⇥ RN ⇥ RN ! R by:

�(t , x , e, e) = F (t , x , e)� F (t , x , e) + H(t).

KEY: There is a non-degenerate critical submanifold with value 0diffeomorphic to the compact L, and non-degenerate critical pointscorresponding to the Reeb chords of ⇤±.

WGH⇤(F ) := H⇤(�1,�✏).

In fact, WGH⇤(F ) ' H⇤(L,⇤+).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 37 / 40

Wrapped Generating Family Cohomology Groups

Given a generating family F : R+ ⇥ M ⇥ RN ! R for (L) ⇢ T ⇤(R+ ⇥ M), and a function H : R+ ! R,

define the sheared difference function � : M ⇥ RN ⇥ RN ! R by:

�(t , x , e, e) = F (t , x , e)� F (t , x , e) + H(t).

KEY: There is a non-degenerate critical submanifold with value 0diffeomorphic to the compact L, and non-degenerate critical pointscorresponding to the Reeb chords of ⇤±.

WGH⇤(F ) := H⇤(�1,�✏).

In fact, WGH⇤(F ) ' H⇤(L,⇤+).

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 37 / 40

(�1,�✏) as a Relative Mapping Cone

Classical Mapping Cone:

Given f : X ! Y , C(f ) := C(X ) [ Y/ ⇠. Induced long exact sequence:

· · · ! Hk (Y )f⇤! Hk (X ) ! Hk+1(C(f )) ! Hk+1(Y )

f⇤! . . . .

Relative Mapping Cone: Given a map g : (X ,A) ! (Y ,B), there is arelative mapping cone C(g) and a long exact sequence:

· · · ! Hk (Y ,B)g⇤! Hk (X ,A) ! Hk+1(C(g)) ! Hk+1(Y ,B)

g⇤! · · · .

(�1,�✏) can be viewed as C( ) where :⇣

�1f+ , �✏f+

!⇣

�1f� , �✏f�

.

So, there is a Cobordism Exact Sequence!

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 38 / 40

(�1,�✏) as a Relative Mapping Cone

Classical Mapping Cone:

Given f : X ! Y , C(f ) := C(X ) [ Y/ ⇠. Induced long exact sequence:

· · · ! Hk (Y )f⇤! Hk (X ) ! Hk+1(C(f )) ! Hk+1(Y )

f⇤! . . . .

Relative Mapping Cone: Given a map g : (X ,A) ! (Y ,B), there is arelative mapping cone C(g) and a long exact sequence:

· · · ! Hk (Y ,B)g⇤! Hk (X ,A) ! Hk+1(C(g)) ! Hk+1(Y ,B)

g⇤! · · · .

(�1,�✏) can be viewed as C( ) where :⇣

�1f+ , �✏f+

!⇣

�1f� , �✏f�

.

So, there is a Cobordism Exact Sequence!

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 38 / 40

(�1,�✏) as a Relative Mapping Cone

Classical Mapping Cone:

Given f : X ! Y , C(f ) := C(X ) [ Y/ ⇠. Induced long exact sequence:

· · · ! Hk (Y )f⇤! Hk (X ) ! Hk+1(C(f )) ! Hk+1(Y )

f⇤! . . . .

Relative Mapping Cone: Given a map g : (X ,A) ! (Y ,B), there is arelative mapping cone C(g) and a long exact sequence:

· · · ! Hk (Y ,B)g⇤! Hk (X ,A) ! Hk+1(C(g)) ! Hk+1(Y ,B)

g⇤! · · · .

(�1,�✏) can be viewed as C( ) where :⇣

�1f+ , �✏f+

!⇣

�1f� , �✏f�

.

So, there is a Cobordism Exact Sequence!Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 38 / 40

Cobordism Long Exact Sequence

Theorem ([Sabloff-LT])Given (⇤�, f�) �(L,F ) (⇤+, f+), there is a long exact sequence:

· · · ! GHk (f�) F! GHk (f+) ! Hk+1(L,⇤+) ! · · · .

F is non-trivial, natural, and behaves nicely under gluings ofcobordisms.

If ⇤� = ; (filling), then GHk (f+) ' Hk+1(L,⇤+).

If L is a concordance, then GHk (f�) ' GHk (f+).

There is a similar story for linearized Legendrian contact homology;[Ekholm, Ekholm-Honda-Kálmán, Golovko]

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 39 / 40

Cobordism Long Exact Sequence

Theorem ([Sabloff-LT])Given (⇤�, f�) �(L,F ) (⇤+, f+), there is a long exact sequence:

· · · ! GHk (f�) F! GHk (f+) ! Hk+1(L,⇤+) ! · · · .

F is non-trivial, natural, and behaves nicely under gluings ofcobordisms.

If ⇤� = ; (filling), then GHk (f+) ' Hk+1(L,⇤+).

If L is a concordance, then GHk (f�) ' GHk (f+).

There is a similar story for linearized Legendrian contact homology;[Ekholm, Ekholm-Honda-Kálmán, Golovko]

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 39 / 40

Cobordism Long Exact Sequence

Theorem ([Sabloff-LT])Given (⇤�, f�) �(L,F ) (⇤+, f+), there is a long exact sequence:

· · · ! GHk (f�) F! GHk (f+) ! Hk+1(L,⇤+) ! · · · .

F is non-trivial, natural, and behaves nicely under gluings ofcobordisms.

If ⇤� = ; (filling), then GHk (f+) ' Hk+1(L,⇤+).

If L is a concordance, then GHk (f�) ' GHk (f+).

There is a similar story for linearized Legendrian contact homology;[Ekholm, Ekholm-Honda-Kálmán, Golovko]

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 39 / 40

Cobordism Long Exact Sequence

Theorem ([Sabloff-LT])Given (⇤�, f�) �(L,F ) (⇤+, f+), there is a long exact sequence:

· · · ! GHk (f�) F! GHk (f+) ! Hk+1(L,⇤+) ! · · · .

F is non-trivial, natural, and behaves nicely under gluings ofcobordisms.

If ⇤� = ; (filling), then GHk (f+) ' Hk+1(L,⇤+).

If L is a concordance, then GHk (f�) ' GHk (f+).

There is a similar story for linearized Legendrian contact homology;[Ekholm, Ekholm-Honda-Kálmán, Golovko]

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 39 / 40

Application: Obstructions to Lagrangian Cobordisms

!"# $% P = t + t + t

-2 2}{&'()

%

*

!"# $% P = + t2{

&'()

}

*++

)

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 40 / 40

Application: Obstructions to Lagrangian Cobordisms

!"# $% P = t + t + t

-2 2}{&'()

%

*

!"# $% P = + t2{

&'()

}

*++

)

!"# $%

!"# $& !"# $%

!"# $&

2

2

2

2

Lisa Traynor (Bryn Mawr) Symplectic and Contact Topology Banff 2013 40 / 40

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