# Questions tagged [partitions]

The partitions tag has no usage guidance.

**1**

vote

**1**answer

59 views

### Enumerating isomorphic subgraphs

For digraphs $G$ and $H$ if we can partition $V(G)$ into a family $\{Q_t\}_{t\in V(H)}$ indexed by $V(H)$ such that $E(G)=\bigcup_{(u,v)\in E(H)}Q_u\times Q_v$, then is every subgraph of $G$ ...

**9**

votes

**0**answers

187 views

### How many partition values are expected to be prime?

Let $p(n)$ be the partition function. Let $P(N)$ count how many $1\leq n\leq N$ are such that $p(n)$ is prime.
Are there any heuristics for how $P(N)$ should behave?
A crude guess at how this ...

**1**

vote

**0**answers

86 views

### extending a partition of a number to get new partition

Let $\lambda = (k_1^{m_1}\,k_2^{m_2})$ where $0<k_1<k_2$ be a partition of $n$ in the power notation.
Let $\mu = p_0^{r_0}\,p_1^{r_1}\,\cdots\, p_t^{r_t} \,(k_1^{m_1}\,k_2^{m_2})\,q_0^{s_0}\,...

**0**

votes

**1**answer

57 views

### partitions such that each number $k$ ($1 \le k \le n$) appear atmost $k$ times

Let $\lambda$ be a partition of $n$ such that each number $k$ ($1 \le k \le n$) appear atmost $k$ times in $\lambda$.
For example : $\lambda = 6+6+6+6+3+2+2+1$
is there any special name for these ...

**0**

votes

**1**answer

70 views

### Minimizing the set of “wrong” edges in $K_\omega$ with $\{0,1\}$-weights

For any set $X$, let $[X]^2 = \big\{\{x,y\}:x\neq y\in X\big\}$.
Let $f:[\omega]^2\to\{0,1\}$ be a function. The principal goal is to find a partition of $\omega$ such that if $m\neq n\in \omega$ ...

**6**

votes

**0**answers

116 views

### Can the partition function $p(n)$ take perfect power values?

Recall that the perfect powers are those integers $m^k$ with $k,m\in\{2,3,\ldots\}$. I don't consider $0$ or $1$ as a perfect power.
Y. Bugeaud, M. Mignotte and S. Siksek [Annals of Math., 2006] ...

**4**

votes

**1**answer

75 views

### Separate the trivial partition by a linear hyperspace

Let $e=[1,1,\ldots,1]\in\mathbb{Z}^n$. I am looking for a way to find a vector $a\in\mathbb{Z}^n$ such that:
$\langle a,e\rangle=0$ and
for every nonnegative $v\in\mathbb{Z}^n$ such that $\langle e,v\...

**3**

votes

**0**answers

90 views

### Integer partitions under divisibility constraint

Consider integer partitions of $x \in \mathbb{N}$ of size $k$ under the constraint that the partition elements are distinct and the ratio of any element to each smaller element is a natural number.
...

**0**

votes

**0**answers

40 views

### Equitable partition

This is in reference to this question:
equitable partitions
Suppose I have this graph enter image description here
whose equitable partition can be taken as $\{1,3,5,7\} ;\{6,2,4,8\}$
But then as ...

**0**

votes

**1**answer

97 views

### Number partitions [closed]

(I'm trying to solve a problem for computer programming. Don't have much of a math background, so I hope I am using the right terminology)
Is there a formula for getting the partitions of a number ...

**3**

votes

**1**answer

208 views

### Generating function for 3 -core partitions: Part II

Let $\lambda$ be an integer partition: $\lambda=(\lambda_1\geq\lambda_2\geq\dots\geq0)$. Further, let $h_u$ denote the hook-length of the cell $u$.
We call $\lambda$ a $t$-core partition if none of ...

**5**

votes

**1**answer

121 views

### Generating function for $3$-core partitions

Let $\lambda$ be an integer partition: $\lambda=(\lambda_1\geq\lambda_2\geq\dots\geq0)$. Further, let $h_u$ denote the hook-length of the cell $u$.
We call $\lambda$ a $t$-core partition if none of ...

**6**

votes

**2**answers

134 views

### A link between hooks, contents and parts of a partition

Let $\lambda$ be an integer partition: $\lambda=(\lambda_1\geq\lambda_2\geq\dots\geq0)$. Denote its conjugate partition by $\lambda'$. For example, if $\lambda=(4,3,1)$ then $\lambda'=(3,2,2,1)$.
...

**5**

votes

**1**answer

95 views

### SYT and contents of a partition

Let $\lambda$ be an integer partition, denote the number of Standard Young Tableaux of shape $\lambda$ by $f_{\lambda}$. This number is computed by the formula
$$f_{\lambda}=\frac{n!}{\prod_{u\in\...

**3**

votes

**1**answer

151 views

### Partitions and $q$-integers

Denote an integer partition of $n$ by $\lambda=(\lambda_1\geq\lambda_2\geq\dots\geq\lambda_k)$ where $\lambda_k>0$. Also recall the $q$-analogues of integer $n$ given by $[n]_q=\frac{1-q^n}{1-q}$. ...

**5**

votes

**2**answers

299 views

### Partitions, $q$-polynomials and generating functions

Recall the integer partition function $P(n)$ with generating function
$$\sum_{n\geq0}P(n)x^n=\prod_{k=1}^{\infty}\frac1{1-x^k}.$$
Let $[n]_q=\frac{1-q^n}{1-q}$ denote the $q$-analogue of the integer $...

**5**

votes

**1**answer

153 views

### Collapsed partitions and generating functions

Given $n\in\Bbb{N}$, the number of (unrestricted) integer partitions of $n$ are given by
$$\sum_{n\geq0}p(n)x^n=\prod_{j\geq1}\frac1{1-x^j}.$$
Define the collapsed partitions of $n$ to be the ...

**7**

votes

**1**answer

193 views

### Partition of 4-tuples

Some $4$-tuples of positive real numbers $(a_1,b_1,c_1,d_1),\dots,(a_n,b_n,c_n,d_n)$ are given, with all $a_i,b_i,c_i,d_i\leq 1$. Can we always partition $\{1,2,\dots,n\}$ into two subsets $X,Y$ so ...

**1**

vote

**1**answer

120 views

### Integer partitions with subset sums “not divisible” by p

I have the following questions: Let $N \in \mathbb{N}$ and
\begin{equation}
\sum_{i=1}^k n_i = N,
\end{equation}
with $n_i \in \mathbb{N}$ for $1 \le i \le k$ and some $k \in \mathbb{N}$, be an ...

**0**

votes

**0**answers

90 views

### Maximizing the sum of hook lengths

Given positive integers $a\geq b$, and $n\in\{1,2,\dots,ab\}$ I am looking for a partition of $n$ into at most $b$ parts of size at most $a$ which maximizes the sum of the hook lengths in the ...

**4**

votes

**1**answer

122 views

### sets of partitions associating any two elements exactly once

There may be a theory that deals with problems like this but I'm not
enough of a mathematician to know what it is. So far I've looked up
braid groups, block design, and the recommended related posts ...

**4**

votes

**1**answer

234 views

### Asymptotic for number of partitions of $n$ into $k$ squares, uniform in $n,k \to +\infty$

Let $p^{(s)}(n)$ be the number of ways of writing the positive integer $n$ as a sum of perfect $s$-powers, where the order does not matter. For example, $p^{(2)}(9) = 4$ since
$$9 = 1^2 + 1^2 + 1^2 + ...

**1**

vote

**0**answers

73 views

### Distance to edge of voronoi diagram

I have $N$ points in an inner product space $S$ with inner product $<\cdot,\cdot>$. Construct a Voronoi partition, $V$, of $S$ with those $N$ points, using the metric induced by the $L_2$ norm. ...

**17**

votes

**1**answer

636 views

### Congruences Ramanujan-style

Let $t\in\Bbb{N}$ and consider the sequences $p_t(n)$ defined by
$$\sum_{n\geq0}p_t(n)x^n=\prod_{i\geq1}\frac1{(1-x^i)^t}=(x;x)_{\infty}^{-t}.$$
The numbers $p_t(n)$ can be regarded as enumerating ...

**1**

vote

**1**answer

227 views

### Hamiltonian cycles — Partition function

Assume a complete undirected graph $G'=(\mathcal{V}',\mathcal{E}')$ and the partirion function:
$$\sum_{\boldsymbol{x}\in \{-1,+1\}^n} \prod_{\left(i,j\right)\in \mathcal{E}'} \left[1+x_{i}x_{j}\...

**1**

vote

**1**answer

128 views

### vector partition

I am interested in partitioning a vector with nonnegative integer entries into a sum of vectors with nonnegative integral entries. For example the partitions like (2,2) = (1,1)+(1,1) = (2,0)+(0,2) = (...

**10**

votes

**0**answers

330 views

### Relation between a continued fraction and partitions

I am interested in the continued fraction
$$\sum\limits_k {{z^{{2^k} - 1}}} = \frac{1}{{1 - \frac{{{T_0}z}}{{1 - \frac{{{T_1}z}}{{1 - \frac{{{T_2}z}}{{1 -{ \ddots }}}}}}}}}.$$
OEIS A104977 states ...

**10**

votes

**0**answers

288 views

### Wherefore art thou a Borcherds Product?

This question essentially asks how can one recognize (or rule out) that a generating function of combinatorial origin may be given as a Borcherds type product. I'll start with a motivational example: ...

**10**

votes

**1**answer

458 views

### Which of these sums appear most often?

Let $N=\{1,2,3,\ldots, n\}$.
We sum all the elements of every nonempty subset of $N$.
Which sum(s) appears most often? (Let's call this sum a champion).
Using a simple pigeonhole argument a champion ...

**4**

votes

**1**answer

112 views

### Partitions of finite sets and their behavior under permutations of the set

The following seems to be useful, and probably well-known, but I can't find a reference for it. If anyone can point me to a textbook or paper which states it, then I'd be grateful.
Consider a ...

**9**

votes

**2**answers

1k views

### A property of 47 with respect to partitions into five parts

Is 47 the largest number which has a unique partition into five parts (15, 10, 10, 6, 6), no two of which are relatively prime?

**3**

votes

**2**answers

204 views

### Generalized partitions and eta functions

Let $\sigma$ be an element of $SL_{24}(\mathbb{Z})$ with its Jordan normal form is diagonal and the eigen values are $\epsilon_j$ for $1 \le j \le 24$ are n th root of unity where $n|N$ and $N$ is the ...

**2**

votes

**1**answer

139 views

### Yet another question about unrestricted partitions

I posed a question called "A Product Related to Unrestricted Partitions". As it stands it is too hard. Here's another variation which is easier to search for and hopefully might shed some light on ...

**5**

votes

**2**answers

248 views

### Upper bound for number of subpartitions of a partition

Let $\alpha = (\alpha_1,\alpha_2,\dots)$ be a partition of the positive integer $n$, that is, a nonincreasing sequence of nonnegative integers $\alpha_j$, with only finitely many nonzero terms, whose ...

**0**

votes

**0**answers

76 views

### Sequences of nested integer partitions

I'm looking for whether the following objects have a name or have been studied at all in the literature: sequences of partitions $(\lambda^{(1)},\lambda^{(2)},\ldots)$ which are nested, i.e. $\lambda^{...

**1**

vote

**0**answers

73 views

### Another characteristic of subsets of (finite) power sets

Consider a finite set $M$, its power set $\mathcal{P}(M)$ and a subset $S$ of the power set, i.e. $S \subset \mathcal{P}(M)$.
Consider as a characteristic of $S$ the function $f_S: \mathbb{N} \...

**4**

votes

**1**answer

225 views

### The number of permutations of a given cycle type that fix a string with a given histogram

Let $\lambda$ and $\mu$ be partitions of some integer $n \geq 1$. Let $d$ be the number of parts in $\mu$ and let $\bar{\mu} \in \{1,\dotsc,d\}^n$ denote the string $1^{\mu_1} 2^{\mu_2} \dotsb d^{\...

**3**

votes

**0**answers

68 views

### Generating function of prime power partitions

By a theorem of Luck, $K^0 (BS_n) \simeq \mathbb{Z} \times \prod_p (\mathbb{Z}_{p}^\wedge)^{r(p,n)}$ where $r(p,n)$ is the number of partitions of $n$ into powers of $p$ (excluding the trivial ...

**4**

votes

**1**answer

120 views

### Partitions of the reals such that closures of partition elements are saturated

Suppose we have a partition $P$ of a set $S$ and a unary set operation $u:\mathscr{P}(S)\to\mathscr{P}(S)$ such that for each $A\in P$ the set $uA$ is saturated with respect to $P$ (a union of ...

**1**

vote

**1**answer

68 views

### Existence of a set partition satisfying some restriction

I am looking in the literature for references to combinatorial result of the kind of the one below. I am quite sure they (or some variations of them) should have been studied intensively, but now I am ...

**3**

votes

**1**answer

77 views

### Source coding lexicographic index of finite alphabet sequence with weight (partitions)

My goal is to determine the lexicographic index of an $M$-ary $n$-sequence $\mathbf{x}$ on the subset with an $M$-weight sum constraint:
$$S = \{ \mathbf{x} \in \{0, \ldots, M-1\}^n: \sum_{j=1}^n x_j =...

**7**

votes

**1**answer

212 views

### What is the growth rate of the number of unoriented cobordism classes?

Let $\Omega_n^O$ denote the abelian group of cobordism classes of closed, unoriented manifolds of dimension $n$, and let $d(n) := \lvert\Omega_n^O\rvert$. What are the asymptotics of $d(n)$?
It's ...

**6**

votes

**0**answers

134 views

### A functional on paths in a symplectic vector space

I'm running into a functional associated to a piecewise smooth curve $\gamma: [0,1] \to V$, where $V$ is a real vector space with a symplectic form $\omega$:
$$ \int_{0 \leq x \leq y \leq 1} \omega(\...

**11**

votes

**0**answers

418 views

### Wilf's conjecture: complementary Bell numbers

The complementary Bell numbers or Uppuluri-Carpenter numbers, denoted $\tilde{B}_n$, can be delivered by
$$G(x):=\sum_{n\geq0}\tilde{B}_n\frac{x^n}{n!}=e^{1-e^x}.$$
Definition. Fix an integer $m\geq0$....

**4**

votes

**1**answer

215 views

### A discrete operator begets even/odd polynomials

Given a function $f(x)$ define the forward shift operator by $Ef(x)=f(x+1)$ and the discrete derivative $\delta f(x)=(E-1)f(x)=f(x+1)-f(x)$.
Given a partition $\lambda=(\lambda_1,\lambda_2,\dots,\...

**6**

votes

**1**answer

256 views

### Are the Fourier coefficients of $\eta(q^m)^m / \eta(q)$ non-negative?

In this paper, the following result is proved.
For any prime $p$, all the Fourier coefficients of
$$\eta(q^p)^p / \eta(q) = q^{\frac{p^2-1}{12}} \prod_{n=1}^\infty (1 - q^{pn})^p (1 - q^{n})^{-1}$$
...

**3**

votes

**1**answer

149 views

### What is the relationship between Partition function and Betti numbers for nilpotent Lie algebras?

Let $p(n)$ denote the number of partitions of a positive integer $n$. It is known that $\{p(n)\}_{n>25}$ is log-concave.
Dietrich Burde said in this MathOF post that property $PF_3$ for partition ...

**8**

votes

**1**answer

320 views

### “strange” diophantine and parity of the partition function

Let $\{x_i\}:=\{x_1=5, x_2=13, x_3=29, x_4=37, x_5=45, \dots \}$
be the sequence of those positive integers of the form
$$
p^{4\alpha+1}n^2$$
in increasing order where $p\equiv 5\pmod 8$ is prime ...

**2**

votes

**0**answers

146 views

### Equi-distribution of the parity of partitions

The integer partition function $p(n)$ has a generating function given by
$$\frac1{(q)_{\infty}}=\sum_{n=0}^{\infty}p(n)q^n$$
with $(q)_{\infty}=\prod_{m=1}^{\infty}(1-q^m)$. The long-standing problem ...

**9**

votes

**2**answers

242 views

### Hooks in a rectangle: Part II

This problem is a follow up on my other MO question.
On the basis of experimental data, I'm prompted to ask:
Question. Let $R(a,b)$ an $a\times b$ rectangular grid, $h_{\square}$ the hook-length ...