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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Partitioning doctors and nurses to hospitals

This problem handles applying doctors and nurses to hospitals. Our data: Hospitals are labeled $h_1 , h_2 , \ldots , h_n$ Doctors are labeled $d_1 , d_2 , \ldots , d_m$ Nurses are labeled $g_1 , g_2 , ...
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1 vote
1 answer
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Minimum number of bits to codify arrays with bounded sums

I have a very big set of non-empty arrays of possibly repeated numbers sorted in a weakly-decreasing order where each number belongs to the interval $[1, 55]$ and the sum of the elements of each array ...
0 votes
1 answer
40 views

Maximal Profit of 'legal' cutting of a board

I'm facing this problem for some time now, I've tried a greedy approach yet I result to trying a DP-ish approach, only to get stuck at a standstill. Given a board of length $n$, and an increasing ...
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Randomized-Select Problem

RANDOMIZED-SELECT A = {12, 0, 4, 3, 5, 7, 9, 2, 8, 11} RAND-SELECT(A, p, q, i) -> ith smallest of A[p.. q] If p = q then return A[q] r <- RAND-Partition (A, p, q) k <- r-p+1 then return A[r] k= ...
3 votes
1 answer
664 views

Is it possible to randomly allocate items to bins such that each distinct allocation has equal probability?

I'm trying to randomly allocate N indistinguishable items over B indistinguishable bins with unlimited capacity. Each allocation should occur with equal probability. An allocation identifies the ...
1 vote
1 answer
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The modularity difference in Louvain algorithm for community detection in graphs

I am interested in the formula of modularity difference between two partitions considered in the Louvain algorithm for community detection in graphs. I give a formal expression of this question below. ...
1 vote
0 answers
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Minimize sum of products of partition [closed]

I have a set of positive integer numbers $A = \{a_1,...,a_N\}$ and I need to find a partition of $A$ into two sets, such that the sum of their products is minimal, i.e., $$ \min_{X,Y : X \cup Y = A} \...
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4 votes
1 answer
101 views

Can almost equal partition problem be solved in polynomial time?

Given a list of positive integers with sum $s$, decide if there is a subset with sum $0.5s$. This is the well-known PARTITION problem, which is NP-hard. What about the following: Given a list of ...
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1 answer
41 views

Complexity of the partition problem with additional constraint

The "classical" partition problem asks whether a given multiset $S$ of positive integers can be partitioned into two subsets $S_1$ and $S_2$ such that the sum of the numbers in $S_1$ equals ...
1 vote
1 answer
28 views

Set partitions into singletons or pairs

I am trying to build an algorithm to compute the partition of a set into singletons or pairs for a set of cardinality 16. I am doing it in MATLAB and came up with codes that either run forever or ...
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Split Bipartite Graph

I have a bipartite graph $G=(U=\{U_1, U_2,\cdots\}, V=\{V_1, V_2,\cdots\} , E)$ such that edges don't "skip" the $V$ vertices. Meaning, if edge $(U_i, V_j)$ doesn't exist, neither will edges ...
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"Icebreaker problem": Dividing set into partitions that maximize pairwise shared memberships?

Suppose I have a set of N*L elements. I wish to generate a sequence of k partitions of size L such that I maximize the number of pairs of elements that share membership of the same partition. What ...
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1 vote
1 answer
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How to partition N numbers into K groups with constraints on the size and sum of each group?

Suppose we are asked to assign $N$ numbers into $K$ mutually exclusive groups. The partition has to satisfy two constraints for each group. The first one is that group $k$ must contain exactly $n_k$ ...
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18 votes
5 answers
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"partial sorting" algorithms (aka "partitioning")

Context: When trying to tame real-world datasets that contain outliers and noise, the interquartile mean is a handy tool: you sort the data, throw away the top and bottom 25% of the data and take the ...
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1 answer
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Partitions with subsets of limited cardinality

Is there a way to compute the number of partitions such that each set in the partition has a cardinality lower or equal to two? If yes, is there also an efficient algorithm to compute these partitions?...
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1 vote
1 answer
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Partition data into two sets of the same size such that the sum of the average distances is maximized

Say I have a set of strings $S=\{s_1, s_2, ..., s_N\}$, and I want to partition $S$ into two sets $S_1$ and $S_2$ equally, i.e., $||S_1|-|S_2||\leq1$. Define the difference of a set as $$Diff(S_k)=\...
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What makes Spectral kmeans clustering better than only Kmeans clustering?

I know that Kmeans clustering is the final step of Spectral clustering. But why is it that the previous steps involved in Spectral clustering make it a more convenient clustering approach? moreover ...
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3 votes
2 answers
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Proof that Balanced Partition is NP-complete

In the Balanced Partition problem, there are $2m$ nonnegative integers with sum $2s$. The goal is to decide whether they can be partitioned into two subsets of $m$ integers and sum $s$. The problem is ...
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Is there an algorithm to efficiently generate all partitions of a set such that no cell contains fewer than k elements of the set?

I am trying to generate partitions of networks to evaluate clustering algorithms. I know that generating all partitions is infeasible (since they grow with Stirling number of the second kind which get ...
1 vote
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Proof that there isn't a $c$-additive approximation to Partition Problem

Define Partition to consist of all tuples $x_1,\ldots,x_n$ which can be divided to two groups in which the sums of the two groups are equal. Is there a proof that there isn't an additive approximation ...
4 votes
1 answer
230 views

Parition a multiset of numbers into two subsets, how to maximize the sum of their medians?

Given a multiset $S$ of numbers, partition it into two subsets $S_1 $ and $S_2$. How to maximize the sum of their medians? For example, the median of {1,2} is ...
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Efficient way of partitionning a set into a fixed number of parts

I am looking for a way of efficiently partitionning a set of consecutive integers in to a set where the number $K$ of parts is given. For instance, for the set {1, 2, 3, 4}, I would like the best way ...
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1 answer
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Similar problem to Subset Sum?

I've been trying to search for a problem which I think could be similar to Subset Sum. The definition of the problem would be as follows: Given k $\in$ $\mathbb{Z}$ and S = {$s_1$,...,$s_n$} s.t. $s_i ...
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2 votes
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Is it known whether PARTITION is NP-complete via first order reductions?

The PARTITION decision problem is defined as follows (taken from COMPUTERS AND INTRACTABILITY from Garey and Johnson): Instance: A finite set $A$ and a size $s(a) \in \mathbb{Z}^{+}$ for each $a \in A$...
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Split the given array into K subsets such that maximum sum of all subsets is minimum

Given an array of $N$ elements, $A$, and a number $K$. ($1 \leq K \leq N$) . Partition the given array into $K$ subsets (they must cover all the elements but can be noncontiguous too). The maximum ...
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Computational Hardness of the $k$-Partition Problem with identical numbers/objects?

The $k$-Partition Problem is NP hard. I want to know if some slight modification of this problem makes it polynomially solvable. Now consider the set $S=\{a_1,\ldots,a_n\}$ of IDENTICAL numbers/...
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Partition a graph into subgraphs such that a partition contains up to X number of a particular node type

I have a DAG graph which contains two types of nodes, A and B. I am looking for a graph partitioning algorithm that can partition a graph in sub-graphs such that each sub-graph contains up to X number ...
2 votes
0 answers
34 views

Partition columns into m groups to maximize absolute value sums

The Task You are given $n$ columns each of length $m$. All values are either $-1$ or $1$. Find an assignment $s$ of each of columns to 1 of $m$ groups in order to maximize the sum of all the absolute ...
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3 votes
1 answer
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Subset sum with only two item types

Suppose we have $r$ copies of the integer $a$ and $t$ copies of the integer $b$, and a capacity $C$. We would like to find the maximum sum of the given integers, that is at most $C$. This is a special ...
1 vote
1 answer
264 views

Partition a set of n integers into m subsets in a way that the maximum subset sum is minimized

Let's say we have a set of n integers. I'm trying to find a way to partition this set into m subsets (empty subsets are not ...
2 votes
1 answer
49 views

Upper-bounding the out-going degree of a graph

Given a graph $G=(V,E)$, I'm looking for a way to orient its edges in a way that will bound its out degree. For example, I can bound the graph's out-degree by $\approx 2\cdot a(G)$, where $a(G)$ is $G$...
1 vote
0 answers
101 views

Does an FPTAS exist for the multiple subset sum problem when m is fixed and c is not a variable?

From Wikipedia Multiple subset sum: The multiple subset sum problem (MSSP) is a generalization of the subset sum problem (SSP): given a multiset $S$ of $n$ integers, and an integer $m$, the goal is to ...
1 vote
1 answer
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SUBSET SUM reduction to PARTITION

This is the PARTITION problem: Given a multiset S of positive integers, decide if it can be partitioned into two equal-sum subsets. This is the SUBSET SUM problem: Given a multiset S of integers ...
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4 votes
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How to sample a perfect partition uniformly at random?

I would like to sample $n$ integers (of some fixed length, say $k$ bits) uniformly at random, and have them partitioned into two sets of equal sum. Since finding such a perfect partition (even if it ...
3 votes
1 answer
149 views

Partition of a $k$-partite graph to minimal number of connected sets

Let $G$ be a $k$-partite directed acyclic graph where the edges are only between two adjacent sets of vertices. I'm trying to partition the graph to the minimal number of connected sets. Sets $A_0, ...
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0 answers
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Partition in a tree shaped distributed network

We are given a synchronic undirected tree shaped network, with $n$ indexed nodes. We know that there is at least one node with at least $\log_k n$ neighbors, $k>1000$, and $k$ is given. We need to ...
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2 votes
1 answer
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Is there an FPTAS for 3-way number partitioning?

The maximization problem of the 3-way number partitioning reads as follows: given $n$ positive integers, partition them into 3 subsets such that the smallest sum is as large as possible. It is known ...
0 votes
1 answer
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Find the minimum sum of distances between sets of points to a straight line in a plane

Given $n$ dots on a plane, such as: n couples ($x_i$,$y_i$) I would like to find a line parallel to y-axis ( $x=b$ ), such that the sum of all of the point's distances from that line will be minimal ...
1 vote
1 answer
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Bounds on graph partitioning

I am trying to find some generic upper bounds on the "standard" graph partitioning problem. Say I have a graph with $|V|$ vertices and $|E|$ edges I want to partition it into two equal $N/...
2 votes
2 answers
111 views

Path graph partitioning, minimizing cut while minimizing maximum total node weight in each part

Suppose there is a path (linear) graph $G = (V, E)$ where $V = \{0, \ldots, n - 1\}$ and $E=\{(0, 1), (1, 2), \ldots, (n - 2, n - 1)\}$, with edge weights $w_e : E \to \mathbb{N}$ and vertex weights $...
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1 vote
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Maximise the value of the minimum weight intra edge

I've been doing review problems for a midterm and I came across this one problem that I haven't been able to solve. The problem essentially says that given a complete graph $G=(V,E)$ partition the ...
3 votes
1 answer
163 views

If a solution to Partition is known to exist, can it be found in polynomial time?

In the Partition problem, there is a set of integers, and the goal is to decide whether it can be partitioned into two sets of equal sum. This problem is known to be NP-complete. Suppose we are given ...
2 votes
2 answers
995 views

Partitioning a graph into subgraphs with overlapping nodes

I'd like to partition a graph into subgraphs with overlapping nodes. To do a simple partition into two, I could use kernighan_lin_bisection algorithm available in ...
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2 answers
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How to reduce the original partition problem to one of its variation?

Here's a statement of the set partition problem: The set partition problem takes as input a set $S = \{ a_1, a_2, ..., a_n \}$(all positive integers). Can $S$ be partitioned into two sets $A$ and $B$ ...
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Optimal partitioning of n-arrays

You're given N integer arrays. Each array can have different size and contains unique values. However same integers can be found in different arrays. The goal is to partition those arrays into K ...
0 votes
0 answers
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Partition graph in a way that minimizes inter-partition edges

I have a graph in which certain vertices are labeled. I need to assign labels to all of the other vertices in a way that minimizes the number of edges between different-label vertices. How can I do ...
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3 votes
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Reduction from 3-partition to ABC-partition

The ABC-partition problem is a variant of 3-partition in which, instead of a single set $S$ with $3 m$ positive integers, there are three sets $A, B, C$ with $m$ positive integers in each. The goal is ...
2 votes
0 answers
104 views

3-partition problem without the restriction to triplets [closed]

In the standard 3-partition problem, there are $3 m$ integers, their sum is $m T$, and they have to be partitioned into $m$ subsets of sum $T$ and size $3$. Consider the variant without the ...
2 votes
1 answer
85 views

Minimum cardinality graph partition that removes specific edges

I have a computational problem that I want to solve. I'm not sure if it has already been studied in literature, or if so under what name. I'd appreciate any pointers to literature or suggestions for ...
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1 answer
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Multi-dimensional Knapsack with Minimum Value constraints for Dimensions

In MDK, we have a vector $W = \{W_1, W_2, ..., W_d\}$ where each element corresponds to the maximum weight for the respective dimension in the knapsack. I want to add a conditional constraint: $V = {...