# Questions tagged [np-hardness]

Questions related to NP-hardness and NP-completeness.

693 questions
Filter by
Sorted by
Tagged with
98 views

### 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 ...
205 views

### 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 ...
83 views

### 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 ...
1 vote
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 ...
5k views

### Implications of unprovability of $P\neq NP$

I was reading "Is P Versus NP Formally Independent?" but I got puzzled. It is widely believed in complexity theory that $\mathsf{P} \neq \mathsf{NP}$. My question is about what if this is ...
34 views

### 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 ...
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 $c_1, \dots, c_n$,...
85 views

### 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 ...
399 views

893 views

### NP-Hardness of a special case of orthogonal packing problem

Let $V$ be a set of $D$-dimensional rectangular shapes. For $d \in \{1,...,D\}$ and $v \in V$, $w_d(v) \in \mathbb{Q}^{+}$ describes the length of $v$ in the dimension $d$. The same notation is used ...
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 ...
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 ...
222 views

### 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 ...
417 views

### Random self reducibility and NP

I was reading the Wikipedia page Random self-reducibility and it states: If an NP-complete problem is non-adaptively random self-reducible the polynomial hierarchy collapses to $\Sigma_3$. I am ...
52 views

### 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 ...
115 views

### 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 ...
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, ...
14k views

### Is finding the minimum regular expression an NP-complete problem?

I am thinking of the following problem: I want to find a regular expression that matches a particular set of strings (for ex. valid email addresses) and doesn't match others (invalid email addresses). ...
75 views

### 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 ...
1 vote
132 views

### 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 ...
674 views

82 views

### 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 ...
3k views

### Techniques for showing that problem is in hardness "limbo"

Given a new problem in $\mathsf{NP}$ whose true complexity is somewhere between $\mathsf{P}$ and being NP-complete, there are two methods that I know of that might be used to prove that resolving this ...
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 $i>1$ ...
101 views

### 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 ...
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 ...
1k views

### Computational Complexity of Computer Vision Problems

What is the computational complexity of computer vision problems (reconstruction, detection, etc.)? Are these problems NP-complete? Are they NP-hard? In most cases this will boil down to determining ...