hankel determinants of catalan, motzkin and schröder...
TRANSCRIPT
![Page 1: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/1.jpg)
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Hankel determinants of Catalan, Motzkin andSchroder numbers and its q-analogues
Masao Ishikawa
Department of MathematicsTottori University
Expansion of Combinatorial Representation Theory,RIMS, Kyoto University, October 23 – 26, 2007
Masao Ishikawa Catalan Hankel Determinants
![Page 2: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/2.jpg)
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Introduction
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Abstract
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In this talk we try to generalize Catalan Hankel determinants andmake a q-analogue. The Catalan numbers are well-know to be thenumber of Dyck paths. We replace the Catalan numbers withMotzkin numbers, Schroder numbers and etc. paths, which countscertain paths in the plane.
Masao Ishikawa Catalan Hankel Determinants
![Page 3: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/3.jpg)
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Contents
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1 Catalan Hankel determinants
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2 A q-analogue
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3 Proof by Lindstrom-Gessel-Viennot theorem
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4 Relation with little q-Jacobi polynomials
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5 Relation with q-Dougall’s formula for basic hypergeometricseries
Masao Ishikawa Catalan Hankel Determinants
![Page 4: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/4.jpg)
. . . . . .
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Contents
.
..
1 Catalan Hankel determinants
.
.
.
2 A q-analogue
.
.
.
3 Proof by Lindstrom-Gessel-Viennot theorem
.
.
.
4 Relation with little q-Jacobi polynomials
.
.
.
5 Relation with q-Dougall’s formula for basic hypergeometricseries
Masao Ishikawa Catalan Hankel Determinants
![Page 5: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/5.jpg)
. . . . . .
.
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Contents
.
..
1 Catalan Hankel determinants
.
.
.
2 A q-analogue
.
.
.
3 Proof by Lindstrom-Gessel-Viennot theorem
.
.
.
4 Relation with little q-Jacobi polynomials
.
.
.
5 Relation with q-Dougall’s formula for basic hypergeometricseries
Masao Ishikawa Catalan Hankel Determinants
![Page 6: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/6.jpg)
. . . . . .
.
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Contents
.
..
1 Catalan Hankel determinants
.
.
.
2 A q-analogue
.
.
.
3 Proof by Lindstrom-Gessel-Viennot theorem
.
.
.
4 Relation with little q-Jacobi polynomials
.
.
.
5 Relation with q-Dougall’s formula for basic hypergeometricseries
Masao Ishikawa Catalan Hankel Determinants
![Page 7: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/7.jpg)
. . . . . .
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Contents
.
..
1 Catalan Hankel determinants
.
.
.
2 A q-analogue
.
.
.
3 Proof by Lindstrom-Gessel-Viennot theorem
.
.
.
4 Relation with little q-Jacobi polynomials
.
.
.
5 Relation with q-Dougall’s formula for basic hypergeometricseries
Masao Ishikawa Catalan Hankel Determinants
![Page 8: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/8.jpg)
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Hankel Determinants
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Hankel matrix
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Let a0, a1, a2,. . . be any sequence of integers. We consider theHankel matrix
A (t)n = (ai+j+t)0≤i,j≤n−1 =
at at+1 . . . at+n−1
at+1 at+2 . . . at+n...
.... . .
...
at+n−1 at+n . . . at+2n−2
of degree n.
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Hankel determinants
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How can we compute det A (t)n ?
Masao Ishikawa Catalan Hankel Determinants
![Page 9: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/9.jpg)
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Hankel Determinants
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Hankel matrix
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Let a0, a1, a2,. . . be any sequence of integers. We consider theHankel matrix
A (t)n = (ai+j+t)0≤i,j≤n−1 =
at at+1 . . . at+n−1
at+1 at+2 . . . at+n...
.... . .
...
at+n−1 at+n . . . at+2n−2
of degree n.
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Hankel determinants
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How can we compute det A (t)n ?
Masao Ishikawa Catalan Hankel Determinants
![Page 10: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/10.jpg)
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Catalan numbers
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Definition
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For n = 0, 1, 2, . . . , The Catalan number Cn is defined to be
Cn =1
n + 1
(2nn
).
The Catalan number Cn counts the Dyck paths from (0, 0) to(2n, 0).
.
Example
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The generating function for the Catalan numbers is given by
1 − √1 − 4t2t
=∑
n≥0
Cntn = 1 + t + 2t2 + 5t3 + 14t4 + · · · .
Masao Ishikawa Catalan Hankel Determinants
![Page 11: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/11.jpg)
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Catalan numbers
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Definition
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For n = 0, 1, 2, . . . , The Catalan number Cn is defined to be
Cn =1
n + 1
(2nn
).
The Catalan number Cn counts the Dyck paths from (0, 0) to(2n, 0).
.
Example
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. ..
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.
The generating function for the Catalan numbers is given by
1 − √1 − 4t2t
=∑
n≥0
Cntn = 1 + t + 2t2 + 5t3 + 14t4 + · · · .
Masao Ishikawa Catalan Hankel Determinants
![Page 12: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/12.jpg)
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Catalan Hankel determinants
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Fact (Mays-Wojciechowski 2000)
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For the Catalan numbers C0, C1, C2,. . . , let
C(t)n = (Ci+j+t)0≤i,j≤n−1
denote the Hankel matrix. Then, for n ≥ 0, the following identitieshold:
det C(0)n = det C(1)
n = 1,
det C(2)n = n + 1,
det C(3)n =
16(n + 1)(n + 2)(2n + 3).
Masao Ishikawa Catalan Hankel Determinants
![Page 13: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/13.jpg)
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Catalan Hankel determinants
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Theorem (Desainte-Catherine-Viennot 1986)
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In general
det C(t)n =
∏
0≤i≤j≤t−1
i + j + 2n
i + j.
holds for t , n ≥ 0.
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Theorem (Krattenthaler 2007)
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det(Cki+1+j
)0≤i,j≤n−1
=∏
1≤i<j≤n
(ki − kj)n∏
i=1
(i + n)!(2ki)!
(2i)!ki!(ki + n)!
for a positive integer n and non-negative integers k1, k2,. . . , kn.
Masao Ishikawa Catalan Hankel Determinants
![Page 14: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/14.jpg)
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Catalan Hankel determinants
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Theorem (Desainte-Catherine-Viennot 1986)
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In general
det C(t)n =
∏
0≤i≤j≤t−1
i + j + 2n
i + j.
holds for t , n ≥ 0.
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Theorem (Krattenthaler 2007)
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det(Cki+1+j
)0≤i,j≤n−1
=∏
1≤i<j≤n
(ki − kj)n∏
i=1
(i + n)!(2ki)!
(2i)!ki!(ki + n)!
for a positive integer n and non-negative integers k1, k2,. . . , kn.
Masao Ishikawa Catalan Hankel Determinants
![Page 15: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/15.jpg)
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Fibonacci Numbers
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Fibonacci Numbers
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Let n ≥ 0. The sequence {Fn} integers defined by F0 = F1 = 1,and
Fn = Fn−1 + Fn−2
is called the Fibonacci sequence.
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Example
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The generating function for the Fibonacci numbers is given by
1
1 − t − t2=
∑
n≥0
Fntn = 1 + t + 2t2 + 3t3 + 5t4 + 8t5 + · · · .
Masao Ishikawa Catalan Hankel Determinants
![Page 16: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/16.jpg)
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Fibonacci Numbers
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Fibonacci Numbers
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Let n ≥ 0. The sequence {Fn} integers defined by F0 = F1 = 1,and
Fn = Fn−1 + Fn−2
is called the Fibonacci sequence.
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Example
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. ..
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The generating function for the Fibonacci numbers is given by
1
1 − t − t2=
∑
n≥0
Fntn = 1 + t + 2t2 + 3t3 + 5t4 + 8t5 + · · · .
Masao Ishikawa Catalan Hankel Determinants
![Page 17: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/17.jpg)
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Catalan determinants and Fibonacci numbers
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Fact (Cvetkovic-Rajkovic-Ivkovic 2002)
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We consider the Hankel matrix
C(t)n = (Ci+j+t + Ci+j+t+1)0≤i,j≤n−1
=
Ct + Ct+1 Ct+1 + Ct+2 . . . Ct+n−1 + Ct+n
Ct+1 + Ct+2 Ct+2 + Ct+3 . . . Ct+n− + Ct+n+1...
... . . ....
Ct+n−1 + Ct+n Ct+n + Ct+n+1 . . . Ct+2n−2 + Ct+2n−1
.
Then the follwoing identities hold for n ≥ 1:
C(0)n = F2n,
C(1)n = F2n+1.
Masao Ishikawa Catalan Hankel Determinants
![Page 18: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/18.jpg)
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Notation
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q-shifted factorials
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We use the notation:
(a; q)∞ =∞∏
k=0
(1 − aqk ),
(a; q)n =n−1∏
k=0
(1 − aqk )
for n = 0, 1, 2, . . . . (a; q)n is called the q-shifted factorial.Frequently used compact natation:
(a1, a2, . . . , ar ; q)∞ = (a1; q)∞(a2; q)∞ · · · (ar ; q)∞,(a1, a2, . . . , ar ; q)n = (a1; q)n(a2; q)n · · · (ar ; q)n
Masao Ishikawa Catalan Hankel Determinants
![Page 19: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/19.jpg)
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Notation
.
q-shifted factorials
.
.
.
. ..
.
.
We use the notation:
(a; q)∞ =∞∏
k=0
(1 − aqk ),
(a; q)n =n−1∏
k=0
(1 − aqk )
for n = 0, 1, 2, . . . . (a; q)n is called the q-shifted factorial.Frequently used compact natation:
(a1, a2, . . . , ar ; q)∞ = (a1; q)∞(a2; q)∞ · · · (ar ; q)∞,(a1, a2, . . . , ar ; q)n = (a1; q)n(a2; q)n · · · (ar ; q)n
Masao Ishikawa Catalan Hankel Determinants
![Page 20: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/20.jpg)
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Notation
.
q-shifted factorials
.
.
.
. ..
.
.
We use the notation:
(a; q)∞ =∞∏
k=0
(1 − aqk ),
(a; q)n =n−1∏
k=0
(1 − aqk )
for n = 0, 1, 2, . . . . (a; q)n is called the q-shifted factorial.Frequently used compact natation:
(a1, a2, . . . , ar ; q)∞ = (a1; q)∞(a2; q)∞ · · · (ar ; q)∞,(a1, a2, . . . , ar ; q)n = (a1; q)n(a2; q)n · · · (ar ; q)n
Masao Ishikawa Catalan Hankel Determinants
![Page 21: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/21.jpg)
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More Notation
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Raising factorials
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If we put a = qα, then
limq→1
(qα; q)n
(1 − q)n= lim
q→1
(1 − qα)
(1 − q)
(1 − qα+1)
(1 − q)· · · (1 − qα+n−1)
(1 − q)
= (α)(α+ 1) · · · (α+ n − 1).
We write (α)n =n−1∏
k=0
(α+ k), which is called the raising factorial.
Masao Ishikawa Catalan Hankel Determinants
![Page 22: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/22.jpg)
. . . . . .
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More Notation
.
Raising factorials
.
.
.
. ..
.
.
If we put a = qα, then
limq→1
(qα; q)n
(1 − q)n= lim
q→1
(1 − qα)
(1 − q)
(1 − qα+1)
(1 − q)· · · (1 − qα+n−1)
(1 − q)
= (α)(α+ 1) · · · (α+ n − 1).
We write (α)n =n−1∏
k=0
(α+ k), which is called the raising factorial.
Masao Ishikawa Catalan Hankel Determinants
![Page 23: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/23.jpg)
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Basic hypergeomrtric series
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Basic hypergeomrtric series
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We shall define the r+1φr basic hypergeomrtric series by
r+1φr
[a1, a2, . . . , ar+1
b1, . . . , br; q, z
]=
∞∑
n=0
(a1, a2, . . . , ar+1; q)n
(q, b1, . . . , br ; q)nzn.
.
Hypergeomrtric series
.
.
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. ..
.
.
If we put ai = qαi and bi = qβi in the above series and let q → 1,then we obtain the r+1Fr hypergeomrtric series
r+1Fr
[α1, α2, . . . , αr+1
β1, . . . , βr; z
]=
∞∑
n=0
(α1)n(α2)n · · · (αr+1)n
n!(β1)n . . . (βr)nzn.
Masao Ishikawa Catalan Hankel Determinants
![Page 24: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/24.jpg)
. . . . . .
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Basic hypergeomrtric series
.
Basic hypergeomrtric series
.
.
.
. ..
.
.
We shall define the r+1φr basic hypergeomrtric series by
r+1φr
[a1, a2, . . . , ar+1
b1, . . . , br; q, z
]=
∞∑
n=0
(a1, a2, . . . , ar+1; q)n
(q, b1, . . . , br ; q)nzn.
.
Hypergeomrtric series
.
.
.
. ..
.
.
If we put ai = qαi and bi = qβi in the above series and let q → 1,then we obtain the r+1Fr hypergeomrtric series
r+1Fr
[α1, α2, . . . , αr+1
β1, . . . , βr; z
]=
∞∑
n=0
(α1)n(α2)n · · · (αr+1)n
n!(β1)n . . . (βr)nzn.
Masao Ishikawa Catalan Hankel Determinants
![Page 25: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/25.jpg)
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Motzkin numbers
.
Definition (Motzkin numbers)
.
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. ..
.
.
The Motzkin number Mn is defined to be
Mn = 2F1
[(1 − n)/2,−n/2
2; 4
].
The Motzkin number Mn counts the number of Moztkin paths from(0, 0) to (n, 0).
.
The generating function
.
.
.
. ..
.
.
The generating function for Motzkin numbers is
∞∑
n=0
Mntn =1 − x −
√1 − 2x − 3x2
2x2
= 1 + x + 2x2 + 4x3 + 9x4 + 21x5 + · · ·
Masao Ishikawa Catalan Hankel Determinants
![Page 26: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/26.jpg)
. . . . . .
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Motzkin numbers
.
Definition (Motzkin numbers)
.
.
.
. ..
.
.
The Motzkin number Mn is defined to be
Mn = 2F1
[(1 − n)/2,−n/2
2; 4
].
The Motzkin number Mn counts the number of Moztkin paths from(0, 0) to (n, 0).
.
The generating function
.
.
.
. ..
.
.
The generating function for Motzkin numbers is
∞∑
n=0
Mntn =1 − x −
√1 − 2x − 3x2
2x2
= 1 + x + 2x2 + 4x3 + 9x4 + 21x5 + · · ·
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Motzkin Hankel determinants
.
Definition
.
.
.
. ..
.
.
For the Motzkin numbers M0, M1, M2,. . . , define the Hankel matrixM(t)
n to be
M(t)n = (Mi+j+t)0≤i,j≤n−1 .
.
Theorem (Aigner 1998)
.
.
.
. ..
.
.
We have
.
.
.
1 det M(0)n = 1 for n ≥ 1,
.
.
.
2 det M(1)n = 1, 0,−1 for n ≡ 0, 1 (mod6), n ≡ 2, 5 (mod6),
n ≡ 3, 4 (mod6), respectively.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Motzkin Hankel determinants
.
Definition
.
.
.
. ..
.
.
For the Motzkin numbers M0, M1, M2,. . . , define the Hankel matrixM(t)
n to be
M(t)n = (Mi+j+t)0≤i,j≤n−1 .
.
Theorem (Aigner 1998)
.
.
.
. ..
.
.
We have
.
.
.
1 det M(0)n = 1 for n ≥ 1,
.
.
.
2 det M(1)n = 1, 0,−1 for n ≡ 0, 1 (mod6), n ≡ 2, 5 (mod6),
n ≡ 3, 4 (mod6), respectively.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Motzkin Hankel determinants
.
Definition
.
.
.
. ..
.
.
For the Motzkin numbers M0, M1, M2,. . . , define the Hankel matrixM(t)
n to be
M(t)n = (Mi+j+t)0≤i,j≤n−1 .
.
Theorem (Aigner 1998)
.
.
.
. ..
.
.
We have
.
.
.
1 det M(0)n = 1 for n ≥ 1,
.
.
.
2 det M(1)n = 1, 0,−1 for n ≡ 0, 1 (mod6), n ≡ 2, 5 (mod6),
n ≡ 3, 4 (mod6), respectively.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Motzkin Hankel determinants
.
Definition
.
.
.
. ..
.
.
For the Motzkin numbers M0, M1, M2,. . . , define the Hankel matrixM(t)
n to be
M(t)n = (Mi+j+t)0≤i,j≤n−1 .
.
Theorem (Aigner 1998)
.
.
.
. ..
.
.
We have
.
.
.
1 det M(0)n = 1 for n ≥ 1,
.
.
.
2 det M(1)n = 1, 0,−1 for n ≡ 0, 1 (mod6), n ≡ 2, 5 (mod6),
n ≡ 3, 4 (mod6), respectively.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Schroder numbers
.
Definition (Schroder numbers)
.
.
.
. ..
.
.
The Schroder number Sn is defined to be
Sn = 22F1
[−n + 1, n + 22
;−1
]
for n ≥ 1 (S0 = 1). The Schroder number Sn counts the number ofSchroder paths from (0, 0) to (2n, 0).
.
The generating function
.
.
.
. ..
.
.
The generating function for Schroder numbers is
∞∑
n=0
Sntn =1 − x −
√1 − 6x + x2
2x
= 1 + 2x + 6x2 + 22x3 + 90x4 + 394x5 + · · ·
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Schroder numbers
.
Definition (Schroder numbers)
.
.
.
. ..
.
.
The Schroder number Sn is defined to be
Sn = 22F1
[−n + 1, n + 22
;−1
]
for n ≥ 1 (S0 = 1). The Schroder number Sn counts the number ofSchroder paths from (0, 0) to (2n, 0).
.
The generating function
.
.
.
. ..
.
.
The generating function for Schroder numbers is
∞∑
n=0
Sntn =1 − x −
√1 − 6x + x2
2x
= 1 + 2x + 6x2 + 22x3 + 90x4 + 394x5 + · · ·
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Schroder Hankel determinants
.
Definition
.
.
.
. ..
.
.
For the Schroder numbers S0, S1, S2,. . . , let
S(t)n = (Si+j+t)0≤i,j≤n−1
be the Schroder Hankel matrix.
.
Theorem
.
.
.
. ..
.
.
We have
.
.
.
1 det S(0)n = 2(n
2) for n ≥ 1,
.
.
.
2 det S(1)n = 2(n+1
2 ) for n ≥ 1,
.
.
.
3 det S(2)n = 2(n+1
2 )(2n+1 − 1) for n ≥ 1.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Schroder Hankel determinants
.
Definition
.
.
.
. ..
.
.
For the Schroder numbers S0, S1, S2,. . . , let
S(t)n = (Si+j+t)0≤i,j≤n−1
be the Schroder Hankel matrix.
.
Theorem
.
.
.
. ..
.
.
We have
.
.
.
1 det S(0)n = 2(n
2) for n ≥ 1,
.
.
.
2 det S(1)n = 2(n+1
2 ) for n ≥ 1,
.
.
.
3 det S(2)n = 2(n+1
2 )(2n+1 − 1) for n ≥ 1.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Schroder Hankel determinants
.
Definition
.
.
.
. ..
.
.
For the Schroder numbers S0, S1, S2,. . . , let
S(t)n = (Si+j+t)0≤i,j≤n−1
be the Schroder Hankel matrix.
.
Theorem
.
.
.
. ..
.
.
We have
.
.
.
1 det S(0)n = 2(n
2) for n ≥ 1,
.
.
.
2 det S(1)n = 2(n+1
2 ) for n ≥ 1,
.
.
.
3 det S(2)n = 2(n+1
2 )(2n+1 − 1) for n ≥ 1.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Schroder Hankel determinants
.
Definition
.
.
.
. ..
.
.
For the Schroder numbers S0, S1, S2,. . . , let
S(t)n = (Si+j+t)0≤i,j≤n−1
be the Schroder Hankel matrix.
.
Theorem
.
.
.
. ..
.
.
We have
.
.
.
1 det S(0)n = 2(n
2) for n ≥ 1,
.
.
.
2 det S(1)n = 2(n+1
2 ) for n ≥ 1,
.
.
.
3 det S(2)n = 2(n+1
2 )(2n+1 − 1) for n ≥ 1.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Schroder Hankel determinants
.
Definition
.
.
.
. ..
.
.
For the Schroder numbers S0, S1, S2,. . . , let
S(t)n = (Si+j+t)0≤i,j≤n−1
be the Schroder Hankel matrix.
.
Theorem
.
.
.
. ..
.
.
We have
.
.
.
1 det S(0)n = 2(n
2) for n ≥ 1,
.
.
.
2 det S(1)n = 2(n+1
2 ) for n ≥ 1,
.
.
.
3 det S(2)n = 2(n+1
2 )(2n+1 − 1) for n ≥ 1.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Moments
.
Moments
.
.
.
. ..
.
.
Here we consider the series
µn =(aq; q)n
(abq2; q)n(n = 0, 1, 2, . . . ).
.
Specializations
.
.
.
. ..
.
.
If we put a = qα, b = qβ and let q → 1, then
µn →(α+ 1)n
(α+ β+ 2)n.
Note that
(12)n
(2)n=
Cn
22n,
(12)n
(1)n=
1
22n
(2nn
),
(32)n
(2)n=
1
22n
(2n + 1
n
).
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Moments
.
Moments
.
.
.
. ..
.
.
Here we consider the series
µn =(aq; q)n
(abq2; q)n(n = 0, 1, 2, . . . ).
.
Specializations
.
.
.
. ..
.
.
If we put a = qα, b = qβ and let q → 1, then
µn →(α+ 1)n
(α+ β+ 2)n.
Note that
(12)n
(2)n=
Cn
22n,
(12)n
(1)n=
1
22n
(2nn
),
(32)n
(2)n=
1
22n
(2n + 1
n
).
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Purpose of this talk
.
Theorem
.
.
.
. ..
.
.
Let n be a positive integer. Then
det (µi+j)0≤i,j≤n−1 = a12 n(n−1)q
16 n(n−1)(2n−1)
×n∏
k=1
(q, aq, bq; q)n−k
(abqn−k+1; q)n−k (abq2; q)2(n−k)
.
.
Corollary
.
.
.
. ..
.
.
Let n be a positive integer and t non-negative integer. Then
det (µi+j+t)0≤i,j≤n−1 = a12 n(n−1)q
16 n(n−1)(2n−1)
{(aq; q)t
(abq2; q)t
}n
×n∏
k=1
(q, aqt+1, bq; q)n−k
(abqn−k+t+1; q)n−k (abqt+2; q)2(n−k)
.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Purpose of this talk
.
Theorem
.
.
.
. ..
.
.
Let n be a positive integer. Then
det (µi+j)0≤i,j≤n−1 = a12 n(n−1)q
16 n(n−1)(2n−1)
×n∏
k=1
(q, aq, bq; q)n−k
(abqn−k+1; q)n−k (abq2; q)2(n−k)
.
.
Corollary
.
.
.
. ..
.
.
Let n be a positive integer and t non-negative integer. Then
det (µi+j+t)0≤i,j≤n−1 = a12 n(n−1)q
16 n(n−1)(2n−1)
{(aq; q)t
(abq2; q)t
}n
×n∏
k=1
(q, aqt+1, bq; q)n−k
(abqn−k+t+1; q)n−k (abqt+2; q)2(n−k)
.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Main Theorem
.
Theorem
.
.
.
. ..
.
.
Let n be a positive integer and k1, k2,. . . , kn non-negative integers.Then we have
det(µki+1+j
)0≤i,j≤n−1
= a(n2)q(n+1
3 )n∏
i=1
(aq; q)ki
(abq2; q)ki+n−1
×∏
1≤i<j≤n
(qki − qkj )n∏
i=1
(bq; q)n−i .
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Methods to prove theorem
.
Proof methods
.
.
.
. ..
.
.
The methods to prove the theorems
Lattice path method (the Lindstrom-Gessel-Viennot theorem)
Orthogonal polynomials and continued fractions (the littleq-Jacobi polynomials)
LU-decompositions (q-Dougall’s formula)
Desnanot-Jacobi adjoint matrix theorem (Dodgson’s formula)
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Methods to prove theorem
.
Proof methods
.
.
.
. ..
.
.
The methods to prove the theorems
Lattice path method (the Lindstrom-Gessel-Viennot theorem)
Orthogonal polynomials and continued fractions (the littleq-Jacobi polynomials)
LU-decompositions (q-Dougall’s formula)
Desnanot-Jacobi adjoint matrix theorem (Dodgson’s formula)
Masao Ishikawa Catalan Hankel Determinants
![Page 45: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/45.jpg)
. . . . . .
.
.
Methods to prove theorem
.
Proof methods
.
.
.
. ..
.
.
The methods to prove the theorems
Lattice path method (the Lindstrom-Gessel-Viennot theorem)
Orthogonal polynomials and continued fractions (the littleq-Jacobi polynomials)
LU-decompositions (q-Dougall’s formula)
Desnanot-Jacobi adjoint matrix theorem (Dodgson’s formula)
Masao Ishikawa Catalan Hankel Determinants
![Page 46: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/46.jpg)
. . . . . .
.
.
Methods to prove theorem
.
Proof methods
.
.
.
. ..
.
.
The methods to prove the theorems
Lattice path method (the Lindstrom-Gessel-Viennot theorem)
Orthogonal polynomials and continued fractions (the littleq-Jacobi polynomials)
LU-decompositions (q-Dougall’s formula)
Desnanot-Jacobi adjoint matrix theorem (Dodgson’s formula)
Masao Ishikawa Catalan Hankel Determinants
![Page 47: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/47.jpg)
. . . . . .
.
.
Methods to prove theorem
.
Proof methods
.
.
.
. ..
.
.
The methods to prove the theorems
Lattice path method (the Lindstrom-Gessel-Viennot theorem)
Orthogonal polynomials and continued fractions (the littleq-Jacobi polynomials)
LU-decompositions (q-Dougall’s formula)
Desnanot-Jacobi adjoint matrix theorem (Dodgson’s formula)
Masao Ishikawa Catalan Hankel Determinants
![Page 48: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/48.jpg)
. . . . . .
.
.
Non-intersecting lattice paths
.
Definition
.
.
.
. ..
.
.
Let D = (V ,E) be an acyclic digraph.
P (u, v) : the set of all directed paths from u to v.
An n-vertex vvv = (v1, . . . , vn) is an n-tuple of vertices of D.
An n-path from uuu = (u1, . . . , un) to vvv = (v1, . . . , vn) is ann-tuple PPP = (P1, . . . ,Pn) such that Pi ∈P (ui , vi).
The n-path PPP is said to be non-intersecting if any two differentpaths Pi and Pj have no vertex in common.
P (uuu,vvv) (resp. P0 (uuu,vvv)) : the set of all (resp.non-intersecting) n-paths from uuu to vvv
uuu is said to be D-compatible with vvv if every path P ∈P(ui , vl)intersects with every path Q ∈P(uj , vk ) whenever i < j andk < l.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Non-intersecting lattice paths
.
Definition
.
.
.
. ..
.
.
Let D = (V ,E) be an acyclic digraph.
P (u, v) : the set of all directed paths from u to v.
An n-vertex vvv = (v1, . . . , vn) is an n-tuple of vertices of D.
An n-path from uuu = (u1, . . . , un) to vvv = (v1, . . . , vn) is ann-tuple PPP = (P1, . . . ,Pn) such that Pi ∈P (ui , vi).
The n-path PPP is said to be non-intersecting if any two differentpaths Pi and Pj have no vertex in common.
P (uuu,vvv) (resp. P0 (uuu,vvv)) : the set of all (resp.non-intersecting) n-paths from uuu to vvv
uuu is said to be D-compatible with vvv if every path P ∈P(ui , vl)intersects with every path Q ∈P(uj , vk ) whenever i < j andk < l.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Non-intersecting lattice paths
.
Definition
.
.
.
. ..
.
.
Let D = (V ,E) be an acyclic digraph.
P (u, v) : the set of all directed paths from u to v.
An n-vertex vvv = (v1, . . . , vn) is an n-tuple of vertices of D.
An n-path from uuu = (u1, . . . , un) to vvv = (v1, . . . , vn) is ann-tuple PPP = (P1, . . . ,Pn) such that Pi ∈P (ui , vi).
The n-path PPP is said to be non-intersecting if any two differentpaths Pi and Pj have no vertex in common.
P (uuu,vvv) (resp. P0 (uuu,vvv)) : the set of all (resp.non-intersecting) n-paths from uuu to vvv
uuu is said to be D-compatible with vvv if every path P ∈P(ui , vl)intersects with every path Q ∈P(uj , vk ) whenever i < j andk < l.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Non-intersecting lattice paths
.
Definition
.
.
.
. ..
.
.
Let D = (V ,E) be an acyclic digraph.
P (u, v) : the set of all directed paths from u to v.
An n-vertex vvv = (v1, . . . , vn) is an n-tuple of vertices of D.
An n-path from uuu = (u1, . . . , un) to vvv = (v1, . . . , vn) is ann-tuple PPP = (P1, . . . ,Pn) such that Pi ∈P (ui , vi).
The n-path PPP is said to be non-intersecting if any two differentpaths Pi and Pj have no vertex in common.
P (uuu,vvv) (resp. P0 (uuu,vvv)) : the set of all (resp.non-intersecting) n-paths from uuu to vvv
uuu is said to be D-compatible with vvv if every path P ∈P(ui , vl)intersects with every path Q ∈P(uj , vk ) whenever i < j andk < l.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Non-intersecting lattice paths
.
Definition
.
.
.
. ..
.
.
Let D = (V ,E) be an acyclic digraph.
P (u, v) : the set of all directed paths from u to v.
An n-vertex vvv = (v1, . . . , vn) is an n-tuple of vertices of D.
An n-path from uuu = (u1, . . . , un) to vvv = (v1, . . . , vn) is ann-tuple PPP = (P1, . . . ,Pn) such that Pi ∈P (ui , vi).
The n-path PPP is said to be non-intersecting if any two differentpaths Pi and Pj have no vertex in common.
P (uuu,vvv) (resp. P0 (uuu,vvv)) : the set of all (resp.non-intersecting) n-paths from uuu to vvv
uuu is said to be D-compatible with vvv if every path P ∈P(ui , vl)intersects with every path Q ∈P(uj , vk ) whenever i < j andk < l.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Non-intersecting lattice paths
.
Definition
.
.
.
. ..
.
.
Let D = (V ,E) be an acyclic digraph.
P (u, v) : the set of all directed paths from u to v.
An n-vertex vvv = (v1, . . . , vn) is an n-tuple of vertices of D.
An n-path from uuu = (u1, . . . , un) to vvv = (v1, . . . , vn) is ann-tuple PPP = (P1, . . . ,Pn) such that Pi ∈P (ui , vi).
The n-path PPP is said to be non-intersecting if any two differentpaths Pi and Pj have no vertex in common.
P (uuu,vvv) (resp. P0 (uuu,vvv)) : the set of all (resp.non-intersecting) n-paths from uuu to vvv
uuu is said to be D-compatible with vvv if every path P ∈P(ui , vl)intersects with every path Q ∈P(uj , vk ) whenever i < j andk < l.
Masao Ishikawa Catalan Hankel Determinants
![Page 54: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/54.jpg)
. . . . . .
.
.
Generating functions
.
Definition
.
.
.
. ..
.
.
We assign a weight xe of each edge e of D.
w(P) : the product of the weights of its edges forP ∈P (u, v).
w(PPP) : the product of the weights of its components forw(PPP) ∈P (uuu,vvv).
GF [S] =∑
PPP∈S w(PPP) for S ⊆P (uuu,vvv).
h(u, v) = GF [P (u, v)] for u, v ∈ V .F(uuu,vvv) = GF [P (uuu,vvv)] for n-vertices u, v.F0(uuu,vvv) = GF [P0 (uuu,vvv)] for n-vertices u, v.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Generating functions
.
Definition
.
.
.
. ..
.
.
We assign a weight xe of each edge e of D.
w(P) : the product of the weights of its edges forP ∈P (u, v).
w(PPP) : the product of the weights of its components forw(PPP) ∈P (uuu,vvv).
GF [S] =∑
PPP∈S w(PPP) for S ⊆P (uuu,vvv).
h(u, v) = GF [P (u, v)] for u, v ∈ V .F(uuu,vvv) = GF [P (uuu,vvv)] for n-vertices u, v.F0(uuu,vvv) = GF [P0 (uuu,vvv)] for n-vertices u, v.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Generating functions
.
Definition
.
.
.
. ..
.
.
We assign a weight xe of each edge e of D.
w(P) : the product of the weights of its edges forP ∈P (u, v).
w(PPP) : the product of the weights of its components forw(PPP) ∈P (uuu,vvv).
GF [S] =∑
PPP∈S w(PPP) for S ⊆P (uuu,vvv).
h(u, v) = GF [P (u, v)] for u, v ∈ V .F(uuu,vvv) = GF [P (uuu,vvv)] for n-vertices u, v.F0(uuu,vvv) = GF [P0 (uuu,vvv)] for n-vertices u, v.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Generating functions
.
Definition
.
.
.
. ..
.
.
We assign a weight xe of each edge e of D.
w(P) : the product of the weights of its edges forP ∈P (u, v).
w(PPP) : the product of the weights of its components forw(PPP) ∈P (uuu,vvv).
GF [S] =∑
PPP∈S w(PPP) for S ⊆P (uuu,vvv).
h(u, v) = GF [P (u, v)] for u, v ∈ V .F(uuu,vvv) = GF [P (uuu,vvv)] for n-vertices u, v.F0(uuu,vvv) = GF [P0 (uuu,vvv)] for n-vertices u, v.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Generating functions
.
Definition
.
.
.
. ..
.
.
We assign a weight xe of each edge e of D.
w(P) : the product of the weights of its edges forP ∈P (u, v).
w(PPP) : the product of the weights of its components forw(PPP) ∈P (uuu,vvv).
GF [S] =∑
PPP∈S w(PPP) for S ⊆P (uuu,vvv).
h(u, v) = GF [P (u, v)] for u, v ∈ V .F(uuu,vvv) = GF [P (uuu,vvv)] for n-vertices u, v.F0(uuu,vvv) = GF [P0 (uuu,vvv)] for n-vertices u, v.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Lidstrom-Gessel-Viennot Theorem
.
Lemma (Lidstrom-Gessel-Viennot)
.
.
.
. ..
.
.
Let uuu = (u1, . . . , un) and vvv = (v1, . . . , vn) be two n-vertices in anacyclic digraph D. Then
∑
π∈Sn
sgnπ F0(uuuπ,vvv) = det[h(ui , vj)]1≤i,j≤n.
In particular, if uuu is D-compatible with vvv, then
F0(uuu,vvv) = det[h(ui , vj)]1≤i,j≤n.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Dyck path
.
Definition (Dyck path)
.
.
.
. ..
.
.
A Dyck path is, by definition, a lattice path in the plane lattice Z2
consisting of two types of steps: rise vectors (1, 1) and fall vectors(1,−1), which never passes below the x-axis. We say a rise vector(resp. fall vector) whose origin is (x, y) and ends at (x + 1, y + 1)(resp. (x + 1, y − 1)) has height y.
-
6
µ R µµ
µ R µ R
(0,0)
(8,2)
x
y
0 1 0
1
2 3 2 3
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Moztkin path
.
Definition (Moztkin path)
.
.
.
. ..
.
.
A Moztkin path is, by definition, a lattice path in Z2 consisting ofthree types of steps: rise vectors (1, 1), fall vectors (1,−1), and(short) level vectors (1, 0) which never passes below the x-axis.
-
6
µ R - µµ
- µ-
R
(0,0)
(9,2)
x
y
0 10
0
12
23
3
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
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Schroder path
.
Definition (Schroder path)
.
.
.
. ..
.
.
A Schroder path is, by definition, a lattice path in Z2 consisting ofthree types of steps: rise vectors (1, 1), fall vectors (1,−1), andlong level vectors (2, 0) which never passes below the x-axis.
-
6
µµ
µ-
RR -
R(0,0) (10,0) x
y
0
1
23
3
21
1
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
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Paths and weights
.
Definition
.
.
.
. ..
.
.
Dm,n : the set of Dyck paths starting from (0, 0) and ending at(m, n).
Mm,n : the set of Moztkin paths starting from (0, 0) andending at (m, n).
Sm,n : the set of Schroder paths starting from (0, 0) andending at (m, n).
.
Definition (weights)
.
.
.
. ..
.
.
Assign the weight ah , bh , ch to each rise vector, fall vector, (shortor long) level vector of height h, respectively.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Paths and weights
.
Definition
.
.
.
. ..
.
.
Dm,n : the set of Dyck paths starting from (0, 0) and ending at(m, n).
Mm,n : the set of Moztkin paths starting from (0, 0) andending at (m, n).
Sm,n : the set of Schroder paths starting from (0, 0) andending at (m, n).
.
Definition (weights)
.
.
.
. ..
.
.
Assign the weight ah , bh , ch to each rise vector, fall vector, (shortor long) level vector of height h, respectively.
Masao Ishikawa Catalan Hankel Determinants
![Page 65: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/65.jpg)
. . . . . .
.
.
Paths and weights
.
Definition
.
.
.
. ..
.
.
Dm,n : the set of Dyck paths starting from (0, 0) and ending at(m, n).
Mm,n : the set of Moztkin paths starting from (0, 0) andending at (m, n).
Sm,n : the set of Schroder paths starting from (0, 0) andending at (m, n).
.
Definition (weights)
.
.
.
. ..
.
.
Assign the weight ah , bh , ch to each rise vector, fall vector, (shortor long) level vector of height h, respectively.
Masao Ishikawa Catalan Hankel Determinants
![Page 66: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/66.jpg)
. . . . . .
.
.
Paths and weights
.
Definition
.
.
.
. ..
.
.
Dm,n : the set of Dyck paths starting from (0, 0) and ending at(m, n).
Mm,n : the set of Moztkin paths starting from (0, 0) andending at (m, n).
Sm,n : the set of Schroder paths starting from (0, 0) andending at (m, n).
.
Definition (weights)
.
.
.
. ..
.
.
Assign the weight ah , bh , ch to each rise vector, fall vector, (shortor long) level vector of height h, respectively.
Masao Ishikawa Catalan Hankel Determinants
![Page 67: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/67.jpg)
. . . . . .
.
.
Paths and weights
.
Definition
.
.
.
. ..
.
.
Dm,n : the set of Dyck paths starting from (0, 0) and ending at(m, n).
Mm,n : the set of Moztkin paths starting from (0, 0) andending at (m, n).
Sm,n : the set of Schroder paths starting from (0, 0) andending at (m, n).
.
Definition (weights)
.
.
.
. ..
.
.
Assign the weight ah , bh , ch to each rise vector, fall vector, (shortor long) level vector of height h, respectively.
Masao Ishikawa Catalan Hankel Determinants
![Page 68: Hankel determinants of Catalan, Motzkin and Schröder ...poisson.ms.u-tokyo.ac.jp/~mi/talks/kyoto07.pdf · In this talk we try to generalize Catalan Hankel determinants and make a](https://reader033.vdocument.in/reader033/viewer/2022060418/5f152adf0207e8319439c0b7/html5/thumbnails/68.jpg)
. . . . . .
.
.
Paths and Continued Fractions
.
Theorem (Flajolet 1980)
.
.
.
. ..
.
.
Stieltjes type continued fraction (Dyck paths):
∑
n≥0
GF[D(2n,0)
]t2n =
1
1 − a0b1t2
1− a1b2 t2
1− a2b3 t2
...
.
Jacobi type continued fraction (Moztkin paths):
∑
n≥0
GF[M(n,0)
]tn =
1
1 − c0t − a0b1t2
1−c1t− a1b2 t2
1−c2 t− a2b3 t2
...
.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Paths and Weights
.
Proposition
.
.
.
. ..
.
.
Schroder path:
∑
n≥0
GF[S(2n,0)
]t2n =
1
1 − c0t2 − a0b1t2
1−c1t2− a1b2 t2
1−c2 t2− a2b3 t2
...
.
Definition (λn)
.
.
.
. ..
.
.
For non-negative integer n, let
λn =
qk−1(1−aqk )(1−abqk )
(1−abq2k−1)(1−abq2k )if n = 2k − 1 is odd,
aqk (1−qk )(1−bqk )
(1−abq2k )(1−abq2k+1)if n = 2k is even.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Paths and Weights
.
Proposition
.
.
.
. ..
.
.
Schroder path:
∑
n≥0
GF[S(2n,0)
]t2n =
1
1 − c0t2 − a0b1t2
1−c1t2− a1b2 t2
1−c2 t2− a2b3 t2
...
.
Definition (λn)
.
.
.
. ..
.
.
For non-negative integer n, let
λn =
qk−1(1−aqk )(1−abqk )
(1−abq2k−1)(1−abq2k )if n = 2k − 1 is odd,
aqk (1−qk )(1−bqk )
(1−abq2k )(1−abq2k+1)if n = 2k is even.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Weights to realize the moment sequence
.
Definition (Weights of Dyck paths)
.
.
.
. ..
.
.
Let P ∈ Dm,n be a Dyck path. We assign the weight 1 to each risevector, and λh to each fall vector of height h.
-
6
µ R µµ
µ R µ R
(0,0)
(8,2)
x
y
1 λ1 1
1
1 λ3 1 λ3
A Dyck Path of weight λ1λ23
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Dyck paths and the generating function
.
Example
.
.
.
. ..
.
.
The generating function of D4,0 equals
GF(D4,0) = λ21 + λ1λ2 =
(1 − aq)(1 − aq2)
(1 − abq2)(1 − abq3)= µ2.
-
6
-
6
µ R µ R µµ R
R(0,0) (4,0) (0,0) (4,0)x x
y y
1 λ1 1 λ1 1
1 λ2
λ1
Dyck Paths in D4,0
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Dyck paths and the generating function
.
Lemma
.
.
.
. ..
.
.
Let m and n be non-negative integers such that m ≡ n (mod2). Putm = 2r and n = 2s if m and n are both even, m = 2r + 1 andn = 2s + 1 if m and n are both odd. Then we have
GF [Dm,n] =[ rs
]q
(aq1+s; q)r−s
(abq2+2s; q)r−s,
where [ rs
]q
=
(q;q)r
(q;q)s(q;q)r−sif 0 ≤ s ≤ r ,
0 otherwise.
Especially
GF [D2m,0] =(aq; q)m
(abq2; q)m= µm.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof by Induction
.
Proof
.
.
.
. ..
.
.
Proceed by induction on m.
-
6
µ
R
x
y
1
λn+1
GF [Dm,n]
GF [Dm−1,n−1]
GF [Dm−1,n+1]
GF [Dm,n] = GF [Dm−1,n−1] + λn+1GF [Dm−1,n+1]
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Stieltjes type continued fraction
.
Corollary (Stieltjes type continued fraction)
.
.
.
. ..
.
.
As a corollary of this lemma, we obtain the Stieltjes type continuedfraction
∑
m≥0
µmtm =1
1 − λ1t
1− λ2 t
1− λ3 t
...
.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Weights to realize the moment sequence
.
Definition (Weights of Moztkin paths)
.
.
.
. ..
.
.
Let P ∈Mm,n be a Moztkin path. We assign the weight λ2h+1 toeach rise vector of height h, λ2h to each fall vector of height h, andλ2h + λ2h+1 to each level vector of height h.
-
6
µ R - µµ
- µ-
R
(0,0)
(9,2)
x
y
λ1 λ2λ0+λ1
λ1
λ3
λ4+λ5
λ5
λ6+λ7λ6
A Moztkin Path of weight λ21λ2λ3λ5λ6(λ0 + λ1)(λ4 + λ5)(λ6 + λ7)
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Dyck paths and the generating function
.
Lemma
.
.
.
. ..
.
.
Let m and n be non-negative integers. Then we have
GF [Mm,n] = q(n2)
[mn
]q
(aq; q)m(1 − abq2n+1)
(abqn+1; q)m+1.
Especially
GF [Mm,0] =(aq; q)m
(abq2; q)m= µm.
.
Corollary (Jacobi type continued fraction)
.
.
.
. ..
.
.
∑
m≥0
µmtm =1
1 − λ1t − λ1λ2t2
1−(λ2+λ3)t− λ3λ4 t2
1−(λ4+λ5)t− λ5λ6 t2
...
.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof by Induction
.
Proof
.
.
.
. ..
.
.
Proceed by induction on m.
-
6
µ-R
x
y
λ2n−1
λ2n + λ2n+1
λ2n+2
GF [Mm,n]
GF [Mm−1,n−1]
GF [Mm−1,n]
GF [Mm−1,n+1]
GF [Mm,n] = λ2n−1GF [Mm−1,n−1] + (λ2n + λ2n+1)GF [Mm−1,n] +λ2n+2GF [Mm−1,n+1]
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Hankel determinants
.
Genetral weights
.
.
.
. ..
.
.
Assign the weight ah , bh to each rise vector, fall vector of height h,respectively.
.
Theorem
.
.
.
. ..
.
.
Let Gm = GF [D2m,0] for non-negative integer m.
.
.
.
1 det (Gm+n)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1a2i−1b2i)n−i
.
.
.
2 det (Gm+n+1)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1)n−i+1 (a2i−1b2i)
n−i
.
.
.
3 det (Gm+n+2)0≤i,j≤n−1 equals
n∑
k=0
k∏
i=1
(a0a1 · · · a2i−3a2
2i−2b1b2 · · · b2i−1b22i−1
)
×k∏
i=1
(a0a1 · · · a2i−1b1b2 · · · b2i)
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Hankel determinants
.
Genetral weights
.
.
.
. ..
.
.
Assign the weight ah , bh to each rise vector, fall vector of height h,respectively.
.
Theorem
.
.
.
. ..
.
.
Let Gm = GF [D2m,0] for non-negative integer m.
.
.
.
1 det (Gm+n)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1a2i−1b2i)n−i
.
.
.
2 det (Gm+n+1)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1)n−i+1 (a2i−1b2i)
n−i
.
.
.
3 det (Gm+n+2)0≤i,j≤n−1 equals
n∑
k=0
k∏
i=1
(a0a1 · · · a2i−3a2
2i−2b1b2 · · · b2i−1b22i−1
)
×k∏
i=1
(a0a1 · · · a2i−1b1b2 · · · b2i)
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Hankel determinants
.
Genetral weights
.
.
.
. ..
.
.
Assign the weight ah , bh to each rise vector, fall vector of height h,respectively.
.
Theorem
.
.
.
. ..
.
.
Let Gm = GF [D2m,0] for non-negative integer m.
.
.
.
1 det (Gm+n)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1a2i−1b2i)n−i
.
.
.
2 det (Gm+n+1)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1)n−i+1 (a2i−1b2i)
n−i
.
.
.
3 det (Gm+n+2)0≤i,j≤n−1 equals
n∑
k=0
k∏
i=1
(a0a1 · · · a2i−3a2
2i−2b1b2 · · · b2i−1b22i−1
)
×k∏
i=1
(a0a1 · · · a2i−1b1b2 · · · b2i)
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Hankel determinants
.
Genetral weights
.
.
.
. ..
.
.
Assign the weight ah , bh to each rise vector, fall vector of height h,respectively.
.
Theorem
.
.
.
. ..
.
.
Let Gm = GF [D2m,0] for non-negative integer m.
.
.
.
1 det (Gm+n)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1a2i−1b2i)n−i
.
.
.
2 det (Gm+n+1)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1)n−i+1 (a2i−1b2i)
n−i
.
.
.
3 det (Gm+n+2)0≤i,j≤n−1 equals
n∑
k=0
k∏
i=1
(a0a1 · · · a2i−3a2
2i−2b1b2 · · · b2i−1b22i−1
)
×k∏
i=1
(a0a1 · · · a2i−1b1b2 · · · b2i)
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Hankel determinants
.
Genetral weights
.
.
.
. ..
.
.
Assign the weight ah , bh to each rise vector, fall vector of height h,respectively.
.
Theorem
.
.
.
. ..
.
.
Let Gm = GF [D2m,0] for non-negative integer m.
.
.
.
1 det (Gm+n)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1a2i−1b2i)n−i
.
.
.
2 det (Gm+n+1)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1)n−i+1 (a2i−1b2i)
n−i
.
.
.
3 det (Gm+n+2)0≤i,j≤n−1 equals
n∑
k=0
k∏
i=1
(a0a1 · · · a2i−3a2
2i−2b1b2 · · · b2i−1b22i−1
)
×k∏
i=1
(a0a1 · · · a2i−1b1b2 · · · b2i)
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof by Lindstrom-Gessel-Viennot theorem
t = 0, n = 4
-
6
µµ R
Rµµ
µµ R
RR
Rµµ
µµ
µµ R
RR
RR
R(0,0) x
y
u4 u3 u2 u1=v1 v2 v3 v4
a0 a0 a0 b1 b1 b1
a1 a1 a1 b2 b2 b2
a2 a2 b3 b3
a3 a3 b4 b4
a4 b5
a5 b6
det (Gm+n)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1a2i−1b2i)n−i
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof by Lindstrom-Gessel-Viennot theorem
t = 1, n = 4
-
6
µ Rµµ
µ RR
Rµµ
µµ
µ RR
RR
Rµµ
µµ
µµ
µ RR
RR
RR
R(0,0) x
y
u4 u3 u2 u1 v1 v2 v3 v4
a0 a0 a0 a0 b1 b1 b1 b1
a1 a1 a1 b2 b2 b2
a2 a2 a2 b3 b3 b3
a3 a3 b4 b4
a4 a4 b5 b5
a5 b6
a6 b7
det (Gm+n+1)0≤i,j≤n−1 =∏n
i=1 (a2i−2b2i−1)n−i+1 (a2i−1b2i)
n−i
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof by Lindstrom-Gessel-Viennot theorem
t = 2, n = 4
-
6
µ R µ Rµµ
µ R µ RR
Rµµ
µµ
µ R µ RR
RR
Rµµ
µµ
µµ
µµ R
RR
RR
RR
R(0,0) x
y
u4 u3 u2 u1 v1 v2 v3 v4
a0 a0 a0 a0 a0b1 b1 b1 b1 b1
a1 a1 a1 b2 b2 b2
a2 a2 a2 a2b3 b3 b3 b3
a3 a3 b4 b4 b4
a4 a4 a4b5 b5 b5
a5 b6
a6 b7
a7 b8
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof of Theorem
.
Theorem
.
.
.
. ..
.
.
Let n be a positive integer. Then
det (µi+j)0≤i,j≤n−1 = a12 n(n−1)q
16 n(n−1)(2n−1)
×n∏
k=1
(q, aq, bq; q)n−k
(abqn−k+1; q)n−k (abq2; q)2(n−k)
.
.
Proof of Theorem
.
.
.
. ..
.
.
The determinant equals
n∏
k=1
(λ2k−1λ2k )n−k =n∏
k=1
n−k∏
i=1
(λ2i−1λ2i)
where
λ2i−1λ2i =aq2i−1(1 − qi)(1 − aqi)(1 − bqi)(1 − abqi)
(1 − abq2i−1)(1 − abq2i)2(1 − abq2i+1).
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof of Theorem
.
Theorem
.
.
.
. ..
.
.
Let n be a positive integer. Then
det (µi+j)0≤i,j≤n−1 = a12 n(n−1)q
16 n(n−1)(2n−1)
×n∏
k=1
(q, aq, bq; q)n−k
(abqn−k+1; q)n−k (abq2; q)2(n−k)
.
.
Proof of Theorem
.
.
.
. ..
.
.
The determinant equals
n∏
k=1
(λ2k−1λ2k )n−k =n∏
k=1
n−k∏
i=1
(λ2i−1λ2i)
where
λ2i−1λ2i =aq2i−1(1 − qi)(1 − aqi)(1 − bqi)(1 − abqi)
(1 − abq2i−1)(1 − abq2i)2(1 − abq2i+1).
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof of Corollary
.
Corollary
.
.
.
. ..
.
.
Let n be a positive integer and t non-negative integer. Then
det (µi+j+t)0≤i,j≤n−1 = a12 n(n−1)q
16 n(n−1)(2n−1)
{(aq; q)t
(abq2; q)t
}n
×n∏
k=1
(q, aqt+1, bq; q)n−k
(abqn−k+t+1; q)n−k (abqt+2; q)2(n−k)
.
.
Proof of Corollary
.
.
.
. ..
.
.
Use
µn+t =(aq; q)n+t
(abq2; q)n+t=
(aq; q)t(aqt+1; q)n
(abq2; q)t(abqt+2; q)n.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof of Corollary
.
Corollary
.
.
.
. ..
.
.
Let n be a positive integer and t non-negative integer. Then
det (µi+j+t)0≤i,j≤n−1 = a12 n(n−1)q
16 n(n−1)(2n−1)
{(aq; q)t
(abq2; q)t
}n
×n∏
k=1
(q, aqt+1, bq; q)n−k
(abqn−k+t+1; q)n−k (abqt+2; q)2(n−k)
.
.
Proof of Corollary
.
.
.
. ..
.
.
Use
µn+t =(aq; q)n+t
(abq2; q)n+t=
(aq; q)t(aqt+1; q)n
(abq2; q)t(abqt+2; q)n.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
The little q-Jacobi polynomials
.
Definition (Andrews-Askey 1977)
.
.
.
. ..
.
.
For n = 0, 1, 2, . . . , the little q-Jacobi polynomials pn(x; a, b; q) isdefined to be
pn(x; a, b; q) =(aq; q)n
(abqn+1; q)n(−1)nq(n
2)2φ1
[q−n, qn+1
aq; q, xq
].
.
Theorem (Three term relation)
.
.
.
. ..
.
.
pn(x) = pn(x; a, b; q) satisfies the three term relation
pn+1(x) ={x − (λ2n + λ2n+1)
}pn(x) − λ2n−1λ2npn−1(x)
where p−1(x) = 0 and p0(x) = 1. Especially, pn(x) is a monicpolynimial of degree n for n = 0, 1, 2, . . . .
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
The little q-Jacobi polynomials
.
Definition (Andrews-Askey 1977)
.
.
.
. ..
.
.
For n = 0, 1, 2, . . . , the little q-Jacobi polynomials pn(x; a, b; q) isdefined to be
pn(x; a, b; q) =(aq; q)n
(abqn+1; q)n(−1)nq(n
2)2φ1
[q−n, qn+1
aq; q, xq
].
.
Theorem (Three term relation)
.
.
.
. ..
.
.
pn(x) = pn(x; a, b; q) satisfies the three term relation
pn+1(x) ={x − (λ2n + λ2n+1)
}pn(x) − λ2n−1λ2npn−1(x)
where p−1(x) = 0 and p0(x) = 1. Especially, pn(x) is a monicpolynimial of degree n for n = 0, 1, 2, . . . .
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Moments
.
Definition (Linear functional)
.
.
.
. ..
.
.
For a polynomial f(x), we define the linear functional L : f 7→ L [f ]by
L [f ] =(aq; q)∞
(abq2; q)∞
∞∑
j=0
(bq; q)j
(q; q)j(aq)j f(qj).
.
Proposition (the moment sequence)
.
.
.
. ..
.
.
From the q-binomial thereom∑∞
j=0(a;q)j
(q;q)jx j =
(ax;q)∞(x;q)∞
, we obtain
L [xn] =(aq; q)n
(abq2; q)n= µn.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Moments
.
Definition (Linear functional)
.
.
.
. ..
.
.
For a polynomial f(x), we define the linear functional L : f 7→ L [f ]by
L [f ] =(aq; q)∞
(abq2; q)∞
∞∑
j=0
(bq; q)j
(q; q)j(aq)j f(qj).
.
Proposition (the moment sequence)
.
.
.
. ..
.
.
From the q-binomial thereom∑∞
j=0(a;q)j
(q;q)jx j =
(ax;q)∞(x;q)∞
, we obtain
L [xn] =(aq; q)n
(abq2; q)n= µn.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Orthogonality
.
Proposition (Andrews-Askey 1977)
.
.
.
. ..
.
.
We have
L [pn(x)pm(x)] =
0 if m , n,
anqn2 (q,aq,bq;q)n
(abq;q)2n(abqn+1;q)n+1if m = n.
.
Proposition (the continued fraction)
.
.
.
. ..
.
.
The above three term equation
pn+1(x) ={x − (λ2n + λ2n+1)
}pn(x) − λ2n−1λ2npn−1(x)
is equvalent to the Jacobi type continued fraction
∑
m≥0
µmtm =1
1 − λ1t − λ1λ2t2
1−(λ2+λ3)t− λ3λ4 t2
1−(λ4+λ5)t− λ5λ6 t2
...
.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Orthogonality
.
Proposition (Andrews-Askey 1977)
.
.
.
. ..
.
.
We have
L [pn(x)pm(x)] =
0 if m , n,
anqn2 (q,aq,bq;q)n
(abq;q)2n(abqn+1;q)n+1if m = n.
.
Proposition (the continued fraction)
.
.
.
. ..
.
.
The above three term equation
pn+1(x) ={x − (λ2n + λ2n+1)
}pn(x) − λ2n−1λ2npn−1(x)
is equvalent to the Jacobi type continued fraction
∑
m≥0
µmtm =1
1 − λ1t − λ1λ2t2
1−(λ2+λ3)t− λ3λ4 t2
1−(λ4+λ5)t− λ5λ6 t2
...
.
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
The Hankel determinants
.
Theorem
.
.
.
. ..
.
.
Let
d(0)n = det A0
n =
∣∣∣∣∣∣∣∣∣∣∣∣∣
µ0 µ1 . . . µn−1
µ1 µ2 . . . µn...
.... . .
...
µn−1 µn . . . µ2n−2
∣∣∣∣∣∣∣∣∣∣∣∣∣Then
d(0)n+1
d(0)n
=n∏
i=1
(λ2i−1λ2i) = anqn2 (q, aq, bq; q)n
(abq; q)2n(abqn+1; q)n+1
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
A proof by the orthogonal polynomials
.
Proof
.
.
.
. ..
.
.
Put
Dn(x) =
∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣
µ0 µ1 . . . µn−1 µn
µ1 µ2 . . . µn µn+1...
.... . .
......
µn−1 µn . . . µ2n−2 µ2n−1
1 x . . . xn−1 xn
∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣
for n = 0, 1, 2, . . . . Then 1
d(0)n
Dn(x) is a monic polynomial of degree
n. Because L [xmDn(x)] = 0 for m < n, we haveL [Dm(x)Dn(x)] = 0 if m , n. From the uniqueness of theorthogonal polynomials with respect to L , we obatin
pn(x) =1
d(0)n
Dn(x).
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof
.
Proof
.
.
.
. ..
.
.
Thus we have
L [xnpn(x)] =1
d(0)n
∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣
µ0 µ1 . . . µn−1 µn
µ1 µ2 . . . µn µn+1...
.... . .
......
µn−1 µn . . . µ2n−2 µ2n−1
µn µn+1 . . . µ2n−1 µ2n
∣∣∣∣∣∣∣∣∣∣∣∣∣∣∣
=d(0)
n+1
d(0)n
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Proof
.
Proof
.
.
.
. ..
.
.
From
pn+1(x) ={x − (λ2n + λ2n+1)
}pn(x) − λ2n−1λ2npn−1(x),
we have
L [xn−1pn+1(x)] = L [xnpn(x)]
− (λ2n + λ2n+1)L [xn−1pn(x)] − λ2n−1λ2nL [xn−1pn−1(x)]
which impliesL [xnpn(x)]
L [xn−1pn−1(x)]= λ2n−1λ2n
Thus we obtaind(0)
n+1
d(0)n
=n∏
i=1
λ2i−1λ2i .
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
Reduction to an identity on hypergeometric series
.
q-Dougall’s formula
.
.
.
. ..
.
.
The LU-decomposition of the Hankel matrix is obatined from thefollowing q-Dougall’s formula:
6φ5
a, qa
12 ,−qa
12 , b , c, d
a12 ,−a
12 , aq/b , aq/c, aq/d
; q,aq
bcd
=(qa, aq/bc, aq/bd, aq/cd; q)∞(aq/b , aq/c, aq/d, aq/bcd; q)∞
.
(See Gasper-Rahman 1990.)
Masao Ishikawa Catalan Hankel Determinants
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. . . . . .
.
.
The end
Thank you!
Masao Ishikawa Catalan Hankel Determinants