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Questions tagged [partitions]

A partition or partitioning of a set A is a collection of disjoint sets whose union yields A.

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2
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1answer
25 views

Conditions under which the 3-partition problem is not strongly NP-complete?

I'm a bit confused about the 3-partition problem. More specifically I'm confused about this from the Wikipedia article: Let B denote the (desired) sum of each subset Si, or equivalently, let the ...
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1answer
20 views

Computing minimum partition of poset of $N$ intervals into chains in $o(N^{2.5})$ time?

Consider a set $P$ of $N$ intervals $\{I_i = (l_i, r_i)\}$ partially ordered according the standard interval order: $I_i < I_j$ iff $r_i \le l_j$. I want to find a minimum cardinality partition of ...
4
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2answers
58 views

Equal partition up to one integer

In the partition problem, the task is to partition $n$ given integers into two subsets $A$ and $B$ with equal sum. This problem is known to be NP-hard, but it becomes easy if the "equal sum" ...
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0answers
19 views

Seeking an algorithm for finding the partition of data on an interval that maximizes the minimum fitness among the blocks

In the paper "An algorithm for optimal partitioning of data on an interval" (link) the authors describe an algorithm for partitioning data on an interval to maximize a fitness function. The fitness ...
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2answers
45 views

How to partition disagreeable people into compatible groups

We have a number of people that must be partitioned into groups, but there may be people that dislike other individuals. Partition the people into the minimum number of groups such that no person is ...
2
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1answer
32 views

Finding partition with maximum number of edges between sets

Given a graph (say in adjacency list form), is there an algorithm to find a partition of vertices such that the number of edges between the two sets of the partition is the maximum possible? For ...
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1answer
27 views

Weighted graph clustering with maximum size constraint

I'm currently trying to solve a clustering problem. I need to cluster/partition an undirected weighted graph into groups that are restricted to size n. I have ...
2
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1answer
50 views

Divide grid so that each box has only one object

Is there an efficient algorithm to divide a 2D space, which contains several different sized rectangles, such that each partition has only a single object. Please see the attached image. I have come ...
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0answers
41 views

Directed Acyclic Graph partition into minimum subgraphs with a constraint

I have this problem, not sure there is a name for it, wherein a Directed Acyclic Graph has different colored nodes. The idea is to partition it into minimum number of subgraphs with the following 2 ...
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1answer
25 views

Sequential subsequence removal with arbitrary predicate

I want to extract sub-sequences from a sequence of float values. The "scale" and range of these values is arbitrary (as I can manipulate it at will) but the "shape" is consistent. For a visual ...
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0answers
13 views

Evaluating clustering/partitioning quality

I'm wondering what are the most common/recognized methods to assess the quality of a clustering. That is because I have developed a tool that can cluster/partition a network (in this case, a public ...
5
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1answer
57 views

NP-hardness even with perturbations

Consider the following problem, which can be called "2-SET-PARTITION": Given two sets of positive numbers, $a_1,\ldots,a_n$ and $b_1,\ldots,b_n$, where $\sum_{i\in[n]}a_i = \sum_{i\in[n]}b_i = 2 S$,...
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32 views

Forming groups of people such that no group has two people that dislike each other

I had an assignment for the graph theory unit of my data structures course. The problem was given as follows: Every person in a class has at least one other person that they dislike and will not ...
4
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1answer
39 views

Partitioning a set so both parts have sum at least $c$ times the total sum

Let $c\in(0,1/2]$ be a constant. Given a set of positive integers with sum $S$, is there a partition into two subsets such that both subsets have sum at least $cS$? If $c=1/2$, this is the famous ...
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0answers
14 views

Balanced $\epsilon$-separated partitioning by a hyperplane

Suppose we have $m$ points in $R^n$ and $\epsilon>0$ is a given constant. How can we find a hyperplane that the number of points that are $\epsilon$-close to it is minimum, with the constraint that ...
2
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1answer
29 views

Partitioning a graph with specific constraints

We have an exercise where we need to find the partitions G[V1] and G[V2] of a graph G=(V,E), that fulfill the following constraints. We also know that there exists at least one partition that fulfills ...
3
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2answers
151 views

Is finding Kth largest element using selection algorithm taking O(n) only if K is fixed?

Wikipedia here https://en.m.wikipedia.org/wiki/Selection_algorithm shows an algorithm using sort of quicksort.. in order to find Kth largest or smallest element taking O(n) time only on average. The ...
1
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1answer
48 views

Partitioning a boolean circuit for automatic parallelization

tl;dr: I have a problem where I have a Boolean circuit and need to implement it with very specific single-thread primitives, such that SIMD computation is significantly cheaper after a threshold. I'm ...
0
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1answer
740 views

Partition array into k subsets

We are given an array and a number K. Partition array into K subsets such that let MaxSum be the maximum sum of among subsets. We have to minimize summation =$$\sum_{i=1}^{k}MaxSum-sum(i) $$ Is ...
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53 views

Split a graph into 2 components with known distribution?

I'm trying to find a method to randomly split a connected planar graph $G$ into two connected components, such that the sum of the weights of vertices in each component are relatively close. (If there ...
2
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0answers
17 views

Is there a more commonly-used term for “multi-pivoting”?

Consider the following computational problem (or rather, task): Given: An array of $A$ of (not necessarily distinct) elements from a fully-ordered finite domain An ordered sequence pivot ...
6
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1answer
129 views

Optimal partitioning of n-tuples

Motivation Recently I was trying to optimize some API calls and reduced the problem to optimization of a cumulative number of identifiers across all the requests. I put some considerable effort into ...
2
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1answer
452 views

Solve PARTITION-INTO-THREE-SETS in pseudo-polynomial time

Let PARTITION-INTO-THREE-SETS be defined as following: Input: Positive integers $a_1, ..., a_n$ Problem: Are there three pairwise disjoint sets $I, J, K \subseteq \{1, ..., n\}$ with $I \cup J \cup ...
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24 views

Partitioning the columns of a matrix

I thought about this problem for a while now and am not able to find a solution for it, be it a direct algorithm or a reduction to a known problem, so I'm asking here: Suppose you have a matrix $A\in\...
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2answers
105 views

How to generate an instance for an NP_hard proof, where each element has two inputs?

I want to prove the NP-hardness of an scheduling problem. The problem seems to be NP-hard in the ordinary sense, so I am trying with the Partition Problem, precisely the Equal Cardinality Partition (...
2
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1answer
52 views

finding separating words (Nerode)

i have found the equivalence classes of given $R_L$ and i need to find the separating words between the equivalence classes(which i don't know how to do). would appreciate if you could explain to me ...
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1answer
246 views

Array subset division with equal sums

Today I stumbled upon a problem which looked like the partition problem but certainly is different. Given array of positive integers, guaranteed to not be divisible into two continious subsets of ...
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1answer
81 views

Complexity of a set partition derived problem

I am stuck at the complexity of the following problem: Given a multiset $S = \{x_1,..., x_n\}$ of $n$ integers and a natural number $k$. Can $S$ be partitioned into multisets $S_1,... S_j$ such that ...
1
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1answer
65 views

Karp hardness of directed monochromatic triangle problem

Monochromatic problem is a classic NP-complete problem. Does the complexity stay NP-complete if we use directed graph? DIRECTED MONOCHROMATIC TRIANGLE problem: Input: A digraph $G(V,A)$ ...
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1answer
73 views

Is this an $NP$-complete problem: Product-2-Partition

I want to prove the NP-hardness of my problem P in scheduling. I was trying with Partition, 3-Partition and Subset product, But neither was successful. Now, I can reduce a problem, say PRODUCT-2-...
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1answer
92 views

Can interval partition solve by sort by different approach

The interval partitioning problem is described as follows: Given a set {1, 2, …, n} of n requests, where ith request starts at time s(i) and finishes at time f(i), find the minimum number of ...
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1answer
60 views

Dijkstra Partitioning Algorithm : Special Case

I have been exploring Dikstra partitioning Algorithm. Below are my given: R = Red W = White B = Blue I have this unpartitioned array. ...
0
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1answer
673 views

Divide an array into two sub arrays such that their sums are equal and possibly maximum

Given an array A, we should partition A into two subarrays whose sums are equal, and that maximizes this sum. We are free to omit items from the subarrays. For example, ...
3
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1answer
60 views

Proving that an equal partition does not exist

We are given a set of $n$ numbers and want to know whether it can be partitioned to two sets with an equal sum. To prove that an equal partition exists, it is sufficient to show a partition. What is ...
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0answers
980 views

k-way set partition problem--dynamic programming solution

I was reading up on the set partition problem on this site of Wikipedia: https://en.m.wikipedia.org/wiki/Partition_problem Among other things, they present a DP approach to solving the equal subset ...
3
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1answer
37 views

Is there an efficient algorithm for WEAK-PARTITION?

Suppose that we are given a list of non-zero integers $(a_1,...,a_n)$ and we want to decide whether there exist $(x_1,...,x_n)$ such that $x_1a_1 + x_2a_2 + ... + x_na_n = 0$, $x_i$ $\in$ $\{-1,0,1\}...
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2answers
349 views

Question regarding Hoare's partitioning scheme and a slight modification to it

This is the pseudocode on wikipedia for Hoare's partitioning scheme: ...
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2answers
105 views

Determine if an array is divisible in pairs of equal sum

I'm currently studying the time complexity of the solution provided by my teacher to this problem, and I can't understand the logic: Let A be an unordered array of positive natural numbers. Write ...
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0answers
67 views

Polygon decomposition into minimum star-shaped polygons

As the title suggests, I'm trying to implement an algorithm to decompose a polygon into the minimum number of star-shaped polygons. I've been searching for quite some time but I can't find any ...
4
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0answers
317 views

Even distribution algorithm

Right now I am working on a distributed system that sends messages from single source to many nodes. It is necessary that certain messages are sent to the same node to ensure order of processing. ...
0
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1answer
59 views

sub-optimal but fast partition generation

I have a set of N integers that I want to partition into m subsets. I want these subsets to be well-balanced wrt some criterion say that minimize the max difference between the size of all subsets. ...
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0answers
88 views

How to enumerate all partitioning of a set to k-subsets of size at most b

I'm looking for an algorithm to generate/enumerate all possibilities for partitioning a set of size $n$ to $k$ non-empty subsets, each with size at most $b$. More specifically, given a set $V$ where $...
2
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1answer
84 views

An algorithm for k-way array partitioning

I am trying to implement samplesort in MPI. The first step of samplesort is to partition the array with $n - 1$ splitters $s_1, s_2, \cdots, s_{n-1}$ into $n$ subsequences, where subsequence $i$ all ...
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0answers
78 views

$k$-partitioning problem via brute force

Given a set of non-negative integers $A = \{a_1,a_2,\dots,a_N \}$, the $k$-partitioning problem is to partition the numbers into $k$ sets $\{A_1,A_2,\dots, A_k\} $ such that the deviation: $$ \...
4
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2answers
67 views

Finding the number of ways to partition $\{1,…,N\}$ into $P_1$ and $P_2$ such that $sum(P_1) = sum(P_2)$ for a given $N$

I am trying to think of how to optimize the following problem: Let $S = \{1,2,...,N\}$. How many ways can $S$ be partitioned into non-empty subsets $P_1$ and $P_2$ such that $sum(P_1) = sum(P_2)$? I ...
2
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1answer
101 views

Set partition refinement with subtrees

In trying to design an algorithm, I needed a datastructure to implement a restricted kind of set partition refinement, where the sets $X$ to split on are subtrees. Specifically, given an arbitrary ...
2
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1answer
247 views

How to partition a tree on a fixed budget of edge cuts?

Suppose I have a tree $T=(V,E,w)$ with vertex weights $w(v)\ge 0$ for all $v\in V$. I want to partition this tree into $k+1$ trees by cutting $k$ edges such that the deviation from the mean of the ...
0
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1answer
392 views

Will a Greedy algorithm give a correct result for minimum partition?

Will a greedy method of picking the item that causes the largest difference each time lead to the optimal result in the minimum partition problem? Let's say I have a set $\{a_1,a_2,a_3,...a_n\}$, now ...
2
votes
1answer
122 views

Given N sets of disjoint subsets, find a set of disjoint subsets such that it satisfies a criteria

Given a collection of sets $S_i$ of disjoint subsets $sub_i$ of a set $X$, find a set $A$ of disjoint subsets $asub$ such that each one of these subsets is subset or equal to at most one subset in ...
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0answers
40 views

Is a minimal deviation version of set partition problem NP-Hard?

I want to know if a specific version (and what´s its name?) of the Set Partitioning Problem is NP-Complete, and if, is NP-Hard? Problem: Given a set of elements $e_i$ where $i={1,...,n}$, each with ...