Questions tagged [np-hardness]

Questions related to NP-hardness and NP-completeness.

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What is the reason to believe that quantum heuristic algorithms can solve NP-Complete problems?

There is an ever going trend to believe that a large number of NP-Complete or NP-Hard problems can be solved using quantum heuristics. I have observed, a common trend, to take any sort of ...
Marion's user avatar
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When Exponential Costs are Essential for NP-Hardness?

In many NP-hard problem there is a budget constraint. Each element $e$ in the instance has a certain cost $c(e)$ and a profit $p(e)$; a feasible solution $S$ for the considered problem cannot exceed ...
John's user avatar
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Permutation generation problem using swaps

This is motivated by Aaronson's post, Probability of generating a desired permutation by random swaps. I am interested in a related problem where the swaps are given in the input. We're given as input ...
Mohammad Al-Turkistany's user avatar
1 vote
1 answer
109 views

3 Matroid Intersection, a Special Case

It is well known that finding a maximum cardinality (or weight) common independent set in the intersection of 3 matroids is APX-Hard. Question: Does this problem remain NP-Hard if one of the matroids ...
John's user avatar
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Reduction of Monotone-1-in-3-SAT to Cubic-Monotone-1-in-3-SAT

3-SAT is an NP-Complete problem. Now given a 3-SAT instance it can be transformed to a Monotone-1-in-3 SAT instance thus even Monotone-1-in-3-SAT is NP-Complete (am aware of this reduction). But, as I ...
J.Doe's user avatar
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56 views

Balls in monochromatic bins

Suppose we have a collection of $m$ balls in $k$ different colors. Let $b_i$ be the number of balls with color $i$, so $\sum_{i=1}^k b_i = m$. Assume we have $n$ bins with capacities $c_1, \dots, c_n$,...
AAArAAA's user avatar
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6 votes
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Cycle packing with degree condition

Given a directed graph where each vertex has the same in-degree as out-degree, I would like to find the maximum number of edge-disjoint cycles. Is this NP-hard? Without the degree condition, the ...
TZM's user avatar
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Is it NP-hard to find an order on a set of strings so that the concatenation is a given string?

Consider the following decision problem over a fixed alphabet $\Sigma$: Input: strings $s_1, \ldots, s_n$ of $\Sigma^*$ and a target string $t \in \Sigma^*$ Output: does there exist a permutation $\...
a3nm's user avatar
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Complexity of Exact Cover problem if containing a Set Cover means there is an Exact Cover

As stated in the question, I'm interested in a variant of Exact Cover that is currently relevant to my research. Specifically, a variant where you are promised that if there is a Set Cover of size $k$,...
Matthew Ferland's user avatar
4 votes
2 answers
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NP-hardness: (planar) directed feedback vertex set problem with bounded degree

My question is the directed version of this one. (I know the results and proofs about feedback vertex set in undirected graphs or undirected planar graphs; so I am concern about the directed feedback ...
Blanco's user avatar
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NP-complete problems on posets?

I'm in the midst of some doctoral research and trying to figure out a particularly tricky reduction. I think my best shot is to reduce from an NP-complete problem on posets, if one exists. I did some ...
Ctenochaetus's user avatar
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139 views

Complexity of $(\Delta-1)$-coloring graphs of maximum degree $\Delta$

Suppose we have a graph $G$ with maximum degree $\Delta$. Deciding if $G$ can be colored with $\Delta$ colors is easy: Brooks' theorem says that this is always possible, unless $G$ is a clique or an ...
Michael Lampis's user avatar
13 votes
1 answer
326 views

Is this a known problem, and is it NP-complete?

Does the following problem have a name? Is it NP-complete? Given a multiset of $n$ positive integers, $S$, and an positive integer $m$, does there exist an $m \times n$ matrix whose rows are ...
Ben G's user avatar
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Is it $NP$-hard to check whether a given algebraic circuit computes permanent?

Given are a natural number $n\in\mathbb{N}$ and a polynomial $P$ in the form of an arithmetic circuit $C$ over $\mathbb{Z}$ (a circuit which only uses $+$ and $\times$ gates and integer constants as ...
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hardness of partition of permutation into a minimum number of monotone subsequences

Given a permutation P, a monotone subsequence is a subsequence (i.e. the elements do not have to be consecutive in P) that increases or decreases. This leads naturally to the following optimization ...
steven kelk's user avatar
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1 answer
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Complexity of induced Steiner Tree problem

Consider the following problem: we are given an undirected graph $G=(V,E)$ and three terminal vertices $t_1,t_2,t_3\in V$. We are asked whether there exists a set of vertices $S\subseteq V$ such that ...
Michael Lampis's user avatar
4 votes
1 answer
98 views

Complexity of finding a path visiting all leaves on a tree while respecting a distance bound

I am interested in the complexity of a specific variant of the Hamiltonian path problem where we want to visit all leaves of a tree while respecting a distance bound. Formally, given an (undirected, ...
a3nm's user avatar
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increasing minimum graph degree by adding edges

My problem: Given a graph $G=(V, E)$ and an integer $\ell$,add a minimum number of edges to $G$ so that in the resulting graph every vertex has degree at least $\ell$. Is there a polynomial-time ...
jpcasti's user avatar
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Is this subsequence problem NP-hard?

Here is yet another "is X NP-hard?" question. The input of the problem is the following: A sequence of $n$ non-negative real numbers $\alpha_1, \ldots, \alpha_n$. Here $n$ is a positive ...
Qalat's user avatar
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Computing real numbers with Turing Machines

Consider the following decision problem: Given a two integers $n$ and $k$, decide whether $k=\lfloor n\pi\rfloor$ Question: Is this problem known to be in $P$? Although this may look like a stupid ...
Mathieu Mari's user avatar
4 votes
1 answer
176 views

Finding a "typical" path

Consider an undirected graph with two distinguished nodes $u\neq v$. How hard is it to find an $u-v$ path, such that its length is as close to the average $u-v$ path length as possible? Formally, for ...
Andras Farago's user avatar
7 votes
1 answer
172 views

Complexity of Maximizing Hamming Distances Below a Threshold

Problem Statement Is the following problem NP-Complete? Input: A collection $S$ of binary strings, with each string of length $m$. Goal: Compute a binary string $s^*$ of length $m$ that mazimizes the ...
B A's user avatar
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1 answer
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Polynomial time solvable in series parallel graph but NP-hard in graph with bounded treewidth

Whether there is a problem to meet the conditions: it is polynomial time solvable in series parallel graphs but NP-hard in graph with bounded treewidth?
zhukui bai's user avatar
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0 answers
51 views

Existence of W[1]-Hard construction from multiple hard problems

I am a research scholar working on parameterized complexity. Currently, I am exploring ways to prove the hardness of a problem by providing W[1]-Hard constructions. A problem is known to be fixed-...
Balchandar Reddy's user avatar
1 vote
1 answer
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Running time of SAT and other EXPTIME algorithms [closed]

I need to propose an algorithm for a NP-hard problem. I use dynamic programming which leads to a running time $O(2^s\cdot n^2), s\leq n.$ The algorithm aims to finding a path in a graph $G(V, E)$ (in ...
user67418's user avatar
2 votes
0 answers
116 views

Complexity of a sum with a product

Is the following problem NP-complete: Input: A set of tuples $T = \left\{ t_i=(a_i,b_i) | 1\le i\le n \right\}$, an integer $k$ and numbers $C,D\in \mathbb Q_{\ge 0}$. Question: Exists a subset $S\...
xtyner's user avatar
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Parameterized intractability for Twin cover

I am currently working on Parameterized algorithms, especially on the complexity of the given problem when parameterized by twin cover as the parameter. I have read the following papers on formulating ...
Balchandar Reddy's user avatar
-1 votes
1 answer
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Parameters: Twin cover and Vertex cover

I am a research scholar, currently working on parameterized algorithms. I am working on a problem and have been exploring various parameters for which the problem remains unsolved. I have read the ...
Balchandar Reddy's user avatar
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74 views

Tractability with respect to multiple parameters

I am working on the decision version of an NP-complete problem. The problem is known to be fixed parameter tractable(FPT) with respect to the solution size $k$ as the parameter. If I consider another ...
Balchandar Reddy's user avatar
6 votes
0 answers
138 views

Computing Sequences with Addition Chains In pseudopolynomial time?

Computing Sequence $a_1, \ldots, a_n$ with addition chains (CSAC) is the problem of finding the shortest sequence $b_1, \ldots, b_m$ with the following properties: $b_1=1$. Every $b_i$ with $i>1$ ...
Alexey Milovanov's user avatar
4 votes
2 answers
346 views

NP-hard problem which is easy on average

I have a feeling like I read somewhere that the Hamiltonian circuit problem is NP-hard, but it is easy on average, or easy for a random instance. However, I cannot find a reference for that, nor an ...
Kolja's user avatar
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1 vote
0 answers
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Find the minimum cost spider joining a root to some leaves

A spider is a tree with at most one vertex of degree greater than 2. This vertex is called the head of the spider. I am interested in the following problem: We are given an undirected graph $G = (V,E)$...
Karagounis Z's user avatar
6 votes
1 answer
234 views

Finding a minimal addition chain for a given number

An addition chain for computing a positive integer $n$ is a sequence of natural numbers starting with $1$ and ending with $n$, such that each number in the sequence is the sum of two previous numbers. ...
Alexey Milovanov's user avatar
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0 answers
58 views

Are the Eigendecomposition and Singular Value Decompositions in the class P?

I can run, for instance, np.linalg.eig or np.linalg.svd on my computer in polynomial time. However, my understanding is that if the intermediate steps require too many bits to express and give NaNs or ...
iamnotacrackpot's user avatar
1 vote
1 answer
113 views

Exact Cover by 3-Sets variation: Partition Into Exact Covers by 3-Sets

In the Exact Cover by 3-Sets problem, we are given a set $X = \{x_1, x_2,\ldots, x_{3n}\}$ and a family of subsets $F = \{\{x_{i_1}, x_{i_2}, x_{i_3}\}\}$ of 3-element subsets of $X$. The question is ...
NayCey's user avatar
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1 vote
1 answer
160 views

Hardness of a class of quadratics

I have a system of inequalities of the form $x_i^2 \le x_j$ with $x_i = a_i + \sum_j \alpha_j b_{i,j}$, the variables are $x_i,\alpha_i$, the values $a_i, b_{i,j} \ge 0$ are known and all $x_i, a_i, \...
user1868607's user avatar
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1 answer
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Is "choosability of subsets" NP-hard?

Let $n\in\mathbb{N}$ be a positive integer, and let ${\cal A}$ be a collection of subsets of $n=\{0,\ldots,n-1\}$. We say ${\cal A}$ has the choosability property if there is $R\subseteq n$ such that $...
Dominic van der Zypen's user avatar
1 vote
0 answers
143 views

Relation between BSS and Turing models

$P_\mathbb R$ is the set of languages decidable in polynomial time over the real $BSS$ machine defined in https://en.wikipedia.org/wiki/Blum%E2%80%93Shub%E2%80%93Smale_machine. Let $0-1-P_\mathbb R=\{...
Turbo's user avatar
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0 votes
1 answer
170 views

The Complexity of Multi-Objective Optimization

Given a vector set $V=\{v_i\}_{i=1}^n$ with $n$ vectors where $v_i\in \mathbb{R}^d$ is a vector and a transfer matrix $\mathbf{W}\in \mathbb{R}^{d_1\times d}$, the target is to select two subsets $V_1=...
Refrain's user avatar
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0 answers
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Complexity of the distance between the average vector of two subsets

Given a vector set $V=\{v_i\}_{i=1}^n$ with $n$ vectors, where $v_i\in \mathbb{R}^d$ is a vector, the target is to select two subsets $V_1=\{v_j\}_{j=1}^{|V_1|} \subset V$ and $V_2=\{v_k\}_{k=1}^{|V_2|...
Refrain's user avatar
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2 votes
1 answer
206 views

Complexity of the Complete (3,2) SAT problem?

A complete $k$-CNF formula is a $k$-CNF formula which contains all clauses of size $k$ or lower it implies. Deciding the satisfiability of a complete $k$-CNF formula is clearly a tractable problem ...
Xavier Labouze's user avatar
2 votes
0 answers
152 views

Which hypergraphs can be simplified by alternatively removing a hyperedge and an isolated vertex?

Let $H = (V, E)$ be a hypergraph, with $V$ the set of vertices and $E \subseteq 2^V$ the set of hyperedges. An elimination sequence on $H$ consists of alternatively removing hyperedges. Specifically, ...
a3nm's user avatar
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What are the capabilities of current Boolean Satisfiability Solvers?

I am wondering how well current Boolean Satisfiability solvers are able to perform — for example, are the best SATsolvers able to solve problems from SATlib?
Nat Kar's user avatar
2 votes
0 answers
73 views

Prize Box Ordering Problem With Position Constraints: Easy or Hard

I have a problem where we have $n$ boxes, each box $i$ have probability $p_i$ of containing a prize with value $h_i > 0$, and remaining probability of containing nothing. Now we are asked to order ...
Linda Cai's user avatar
2 votes
1 answer
150 views

Is the weighted sum of subset prefix product problem NP-hard?

I have this strange problem where we have a set of positive numbers $M$, a fixed number $n$, and a function $f: M \rightarrow R^+$ mapping each number in M to another positive number. We want to know ...
Linda Cai's user avatar
2 votes
0 answers
123 views

SUBSET SUM "with error"

Has a SUBSET-SUM "with error" variant been studied - and with error, I mean, instead of a single target value $k$, a target interval $[k-\varepsilon,k+\varepsilon]$ ($\varepsilon>0$ very ...
CSSTUDENT's user avatar
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5 votes
0 answers
107 views

Joint Scheduling Problem with Variables Arrival Times

The scheduling problem $1\bigl|r_j\bigl|\Sigma\,U_j$ is strongly NP-hard but when preemption is allowed the scheduling problem $1\bigl|pmtn,r_j\bigl|\Sigma\,U_j$ becomes strongly polynomial. I have a ...
zdm's user avatar
  • 325
2 votes
1 answer
123 views

Optimal solution for partitioning convex polygon

Given a convex polygon $P$ (possibly) with holes. We want to partition $P$ into a minimum number of connected interior-disjoint polygons $P_1,...P_s$. The definition of restriction on the pieces is ...
sn3jd3r's user avatar
  • 133
2 votes
1 answer
287 views

The complexity of 3SAT

It is well known that 3SAT remains NP-complete if every variable occurs exactly twice positively, exactly once negated. then, does 3SAT remain NP-complete if every variable occurs exactly once ...
zhukui bai's user avatar
1 vote
0 answers
111 views

Is counting the union of power sets NP-complete?

Say we have $n$ sets $A_1,\dots,A_n$ with elements from a universal set $U$. We want to compute the cardinality of $\cup_{i=1}^n 2^{A_i}$ or at least decide on non-trivial bounds. Is this problem NP-...
Joseph Mckinsey's user avatar

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