A binary hook-length formula? Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern) Announcing the arrival of Valued Associate #679: Cesar Manara Unicorn Meta Zoo #1: Why another podcast?Finite nilpotent orbits: GL(n,q)-conjugacy classes and a partial order on partitionsLinking formulas by Euler, Pólya, Nekrasov-Okounkovpartitions into odd parts vs hooks and symplectic contentshooks and contents: Part IHooks in a staircase partition: Part IA link between hooks, contents and parts of a partitionA link between hooks and contents: Part IIGenerating function for $3$-core partitionsGenerating function for 3 -core partitions: Part IIhook-length formula: “Fibonaccized” Part I
A binary hook-length formula?
Planned maintenance scheduled April 23, 2019 at 23:30 UTC (7:30pm US/Eastern)
Announcing the arrival of Valued Associate #679: Cesar Manara
Unicorn Meta Zoo #1: Why another podcast?Finite nilpotent orbits: GL(n,q)-conjugacy classes and a partial order on partitionsLinking formulas by Euler, Pólya, Nekrasov-Okounkovpartitions into odd parts vs hooks and symplectic contentshooks and contents: Part IHooks in a staircase partition: Part IA link between hooks, contents and parts of a partitionA link between hooks and contents: Part IIGenerating function for $3$-core partitionsGenerating function for 3 -core partitions: Part IIhook-length formula: “Fibonaccized” Part I
$begingroup$
This is purely exploratory and inspired by curiosity.
Setup: For an integer $k>0$, let $k=sum_jgeq0k_j2^j$ be its binary expansion and denote the sum of its digits by $eta(k):=sum_jk_j$. Further, introduce a binary factorial
$$[n]!_b:=eta(1)eta(2)cdotseta(n).$$
Given an integer partition $lambda$, let $Y_lambda$ be the corresponding Young diagram. If $square$ a cell in $Y_lambda$, construct its hook-length $h_square$ in the usual manner but replace it by $eta(h_square)$.
For example, take $lambda=(3,2,1)$ then its multiset of hooks is $h_square:squarein Y_lambda=5,3,1,3,1,1$ which shall be replaced by $eta(h_square):squarein Y_lambda=2,2,1,2,1,1$.
Naturally, we define the (new) product of hook-lengths and denote (with an abuse of notation)
$$H_lambda=prod_squareinlambdaeta(h_square).$$
If $lambdavdash n$, it is easy to verify that $frac[n]!_bH_lambda$ is an integer.
QUESTION. What do these integer count?
$$sum_lambdavdash nfrac[n]!_bH_lambda.$$
The first few values are: $1, 2, 3, 7, 10, 23, 52, 82, 117, 258, dots$ but not listed on OEIS.
nt.number-theory co.combinatorics rt.representation-theory partitions
$endgroup$
add a comment |
$begingroup$
This is purely exploratory and inspired by curiosity.
Setup: For an integer $k>0$, let $k=sum_jgeq0k_j2^j$ be its binary expansion and denote the sum of its digits by $eta(k):=sum_jk_j$. Further, introduce a binary factorial
$$[n]!_b:=eta(1)eta(2)cdotseta(n).$$
Given an integer partition $lambda$, let $Y_lambda$ be the corresponding Young diagram. If $square$ a cell in $Y_lambda$, construct its hook-length $h_square$ in the usual manner but replace it by $eta(h_square)$.
For example, take $lambda=(3,2,1)$ then its multiset of hooks is $h_square:squarein Y_lambda=5,3,1,3,1,1$ which shall be replaced by $eta(h_square):squarein Y_lambda=2,2,1,2,1,1$.
Naturally, we define the (new) product of hook-lengths and denote (with an abuse of notation)
$$H_lambda=prod_squareinlambdaeta(h_square).$$
If $lambdavdash n$, it is easy to verify that $frac[n]!_bH_lambda$ is an integer.
QUESTION. What do these integer count?
$$sum_lambdavdash nfrac[n]!_bH_lambda.$$
The first few values are: $1, 2, 3, 7, 10, 23, 52, 82, 117, 258, dots$ but not listed on OEIS.
nt.number-theory co.combinatorics rt.representation-theory partitions
$endgroup$
add a comment |
$begingroup$
This is purely exploratory and inspired by curiosity.
Setup: For an integer $k>0$, let $k=sum_jgeq0k_j2^j$ be its binary expansion and denote the sum of its digits by $eta(k):=sum_jk_j$. Further, introduce a binary factorial
$$[n]!_b:=eta(1)eta(2)cdotseta(n).$$
Given an integer partition $lambda$, let $Y_lambda$ be the corresponding Young diagram. If $square$ a cell in $Y_lambda$, construct its hook-length $h_square$ in the usual manner but replace it by $eta(h_square)$.
For example, take $lambda=(3,2,1)$ then its multiset of hooks is $h_square:squarein Y_lambda=5,3,1,3,1,1$ which shall be replaced by $eta(h_square):squarein Y_lambda=2,2,1,2,1,1$.
Naturally, we define the (new) product of hook-lengths and denote (with an abuse of notation)
$$H_lambda=prod_squareinlambdaeta(h_square).$$
If $lambdavdash n$, it is easy to verify that $frac[n]!_bH_lambda$ is an integer.
QUESTION. What do these integer count?
$$sum_lambdavdash nfrac[n]!_bH_lambda.$$
The first few values are: $1, 2, 3, 7, 10, 23, 52, 82, 117, 258, dots$ but not listed on OEIS.
nt.number-theory co.combinatorics rt.representation-theory partitions
$endgroup$
This is purely exploratory and inspired by curiosity.
Setup: For an integer $k>0$, let $k=sum_jgeq0k_j2^j$ be its binary expansion and denote the sum of its digits by $eta(k):=sum_jk_j$. Further, introduce a binary factorial
$$[n]!_b:=eta(1)eta(2)cdotseta(n).$$
Given an integer partition $lambda$, let $Y_lambda$ be the corresponding Young diagram. If $square$ a cell in $Y_lambda$, construct its hook-length $h_square$ in the usual manner but replace it by $eta(h_square)$.
For example, take $lambda=(3,2,1)$ then its multiset of hooks is $h_square:squarein Y_lambda=5,3,1,3,1,1$ which shall be replaced by $eta(h_square):squarein Y_lambda=2,2,1,2,1,1$.
Naturally, we define the (new) product of hook-lengths and denote (with an abuse of notation)
$$H_lambda=prod_squareinlambdaeta(h_square).$$
If $lambdavdash n$, it is easy to verify that $frac[n]!_bH_lambda$ is an integer.
QUESTION. What do these integer count?
$$sum_lambdavdash nfrac[n]!_bH_lambda.$$
The first few values are: $1, 2, 3, 7, 10, 23, 52, 82, 117, 258, dots$ but not listed on OEIS.
nt.number-theory co.combinatorics rt.representation-theory partitions
nt.number-theory co.combinatorics rt.representation-theory partitions
edited 2 days ago
T. Amdeberhan
asked 2 days ago
T. AmdeberhanT. Amdeberhan
18.5k230132
18.5k230132
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add a comment |
1 Answer
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$begingroup$
I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.
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$begingroup$
I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.
$endgroup$
add a comment |
$begingroup$
I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.
$endgroup$
add a comment |
$begingroup$
I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.
$endgroup$
I am afraid they are not always integers. Take large $p$ and $n=2^2p-1$. Then $[n]!_b$ is divisible by $p^N$ for $N=2pchoose p+1$. And $[2n+1]!_b$ by $p^K$ for $K=2p+1choose p+2p+1<2N$. Then for $2times N$ diagram we get $p$ in the denominator.
answered 2 days ago
Fedor PetrovFedor Petrov
52.4k6122241
52.4k6122241
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