Questions tagged [integer-partitions]

Use this tag for questions related to ways of writing a positive integer as a sum of positive integers.

In number theory and combinatorics, a partition of a positive integer $n$ is a way of writing $n$ as a sum of positive integers. Two sums that differ only in the order of their summands (also called parts) are considered the same partition. For example, all of the partitions of $4$ are $1 + 1 + 1 + 1$, $2 + 1 + 1$, $2 + 2$, $3 + 1$, or $4$.

The number of partitions of $n$ is given by the partition function $p(n)$. For the example above, $p(4) = 5$.

Partitions can be visualized graphically with Ferrers diagrams.

Partitions have applications in symmetric polynomials, the symmetric group, and group representations.

1405 questions
1
vote
1 answer

Change in Partition for Geometric Mean if Sum Increases

Suppose we have a fixed constant $k$, and a number $x$, where we need to partition $x$ into the sum of $k$ integers: $$x = x_1+\cdots+x_k$$ such that the geometric mean $\prod_{i=1}^k x_i$ is maximized. If we want to partition $x+1$ into the sum of…
Nick
  • 167
1
vote
1 answer

Partition parts

Consider the partitions of $n$. For $n = 5,7,9,\ldots$, it appears as if the number of pairwise partitions $\{a,b\}$, where both $a$ and $b$ are composite, equals the total number of individual odd composite parts of $n-2$. Take $n=13$ for…
jnthn
  • 361
1
vote
1 answer

integer partition with negative numbers

Let $d > 0$. I am trying to find the ways of having $$ \lvert n_1 \rvert + \cdots + \lvert n_d \rvert =k $$ And $$ \lvert n_1 \rvert + \cdots + \lvert n_d \rvert \leq k $$ for some fixed $k \geq 0$ and $(n_1,\dots,n_d) \in \mathbb{Z}^d$. I…
1
vote
0 answers

Partitioning integer with subtraction allowed

Let's imagine you want to get a number $A$ from a set of number $M$. You might use only +/- between the numbers and your job is to determine, whether it's possible to get the result $A$ or not. So let's say $A = 12$ and $M =\{ 3,4,5 \} $ then the…
1
vote
1 answer

Question on lower & upper Riemann sums for piecewise.

Partition{$\frac{-\pi}{6},3,2\pi$} $f(x)= 1/2$ if x is rational $sin(x)$ if x is irrational. Im not sure if im doing it correctly: $L(P,f)=(3-\frac{-\pi}{6})(sin(\frac{-\pi}{6}))+(2\pi-3)(sin(2\pi))$ Another question. If I have a function f(x) =…
1
vote
1 answer

On a theorem (1.7) in Macdonald's Symmetric Functions and Hall Polynomials

I'm using Macdonald's Symmetric Functions and Hall Polynomials as a reference, and here's what's given: Theorem (1.7, Page 3): Let $\lambda$ be a partition and let $m \geq \lambda_1$, $n \geq \lambda'_1$. Then the $m+n$ numbers $$\lambda_i + n - i…
1
vote
0 answers

Number of partitions of a $\mathbb{N}^n$ vector

Using power series, we can find an formula for the partitions of an integer. Can we do the same for the partitions of a vector? (I tried to apply the same technique, but failed due to the fact that the integer partitions of each component depends on…
Raito
  • 1,890
  • 11
  • 17
1
vote
1 answer

Number of Integer Solutions for $x_1 + x_2 + x_3 + x_4 = 15$ where $-5 \le x_i \le 10$

I am trying to find the number of Integer Solutions for $x_1 + x_2 + x_3 + x_4 = 15$ where $-5 \le x_{i_{\in [4]}} \le 10$ I know if $x_i$s are all non-negative integers, it is a number partition of 15 however, this case a bit tricky with the…
1
vote
0 answers

Could someone explain partition (number theory) to me.

Hello I am a 15 year old taking gcse maths and further maths and computer science. I need to know about partition of numbers for an algorithm that i am working on. However, partition is degree level maths and not something that i understand at all.…
1
vote
1 answer

Number of partitions for N without repetition

I'm trying to figure out a formula that returns the number of strict partitions (no duplicate values) of n. For example: 5 would yield 3: 5, 4+1, 3+2 I only need the number of unique partitions, not the partitions themselves. I did come across …
1
vote
0 answers

Computing Truncations

Let $P(x)=\sum_{n=0}^{\infty} p_nx^n$ be the partition generating function, and let $P^*(x)=\sum_{n=0}^{\infty} p^*_nx^n$, where $$p^*_n = \binom{\text{number of partitions of }n}{\text{into an even number of parts}} - \binom{\text{number of…
Xarqar
  • 91
1
vote
1 answer

Occurrence of element in all contiguous partitionings of a set

For a set S={1,2,3}, I perform all possible contiguous partitioning on the set to get {{1},{2},{3}},{{1,2},{3}},{{1},{2,3}},{{1,2,3}}. Lets call each partition a piece. I need to efficiently calculate sum of the following term over all the…
1
vote
0 answers

Partitions of $n$ vs $(n-k_0)! $

Let $p(n)$ denote the partitions of $n$. It's easy to prove that $p(n) < n!$ (for n>2). I want to prove that if $n \ge 6$ then $(n-2)! > p(n)$. Or more generally let $k_0\in \mathbb{N}$ be a fixed positive integer and suppose that for some $n_0 \in…
1
vote
0 answers

Partition Function Breakdown

Let $g(n,k)$ be the number of partitions of $n$ into exactly $k$ parts, in which no part is a $1$. Show that $$g(n,k) = g(n-2,k-1) + g(n-k,k).$$ How would I show this?
1
vote
2 answers

Unique sum of $k$ triangular numbers into $k$ triangular numbers?

First things first. I've made this a seperate thread off my previous topic so that these topics don't conflict if I'd posted this to my previous question. I believe any $k$ triangular numbers will have a unique sum, such that they can not be…
Mach9
  • 135