Questions tagged [counting-complexity]

How hard is counting the number of solutions?

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Crafting ${NP}^{\#P}$-complete problems

Some related posts: Is $coNP^{\#P}=NP^{\#P}=P^{\#P}$? $\mathsf{NP^{PP}}$ vs $\mathsf{P^{PP}}$ I needed a complete problem for the class ${NP}^{\#P}$ for a reduction to show the hardness of some other ...
Habri's user avatar
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Coefficients of a determinant of a matrix of univariate polynomials is in $GapL$

Given any matrix of univariate polynomials of degree $\leq n^{O(1)}$ then prove that the coefficent of $x^i$ in the determinant of the matrix is in $GapL$ Hint: Use Mahajan-Vinay's result of ...
Soham Chatterjee's user avatar
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Computational complexity of finding the $n$th Dedekind Number

Recently, two independent groups of researchers exactly calculated the $9$th Dedekind Number (see e.g. Quanta). The $n$th Dedekind Number counts the number of antichains consisting of subsets of $\{1,...
Clay Thomas's user avatar
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Do fast satisfiability algorithms imply fast algorithms for parity SAT?

$\oplus$SAT is the problem of deciding if the number of satisfying assignments to a CNF formula is odd (and is the standard complete problem for the class $\oplus$P, or Parity-P). Suppose we have a ...
Michael Lampis's user avatar
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FPRAS to estimate the probability to get a cyclic subgraph of a directed graph

Consider a directed graph $G = (V, E)$ whose edges are annotated with independent probabilities of existence. This gives a probability distribution on the subgraphs of $G$; for instance, if each edge ...
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Complexity of permanent verification

Consider the problem of permanent verification: $\bullet \ $ Given a $n\times n$ matrix $A$ with entries in $\{0,1\}$, and given $k\ge 0$, does $Per(A)=k$? Question: Is it known to be NP-hard? Should ...
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Complexity of "opposite" version of a variant of #Positive-2-SAT

In this post ,I introduced a new variant of #Positive-2-SAT . This version of problem puts restrictions on the inputs of the #Positive-2-SAT such that we can only choose at max only 2 clauses from ...
Anuj's user avatar
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Perm and Det mod $2^k$ - I

Given a $0/1$ square matrix, the permanent and determinant modulo $2^k$ is in $\oplus P$ and $\oplus L$ respectively for any fixed $k$. In fact both are in $\oplus L$ (in fact in $\oplus SPACE(k^2\log ...
Turbo's user avatar
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Extending fagin’s theorem for #P (for arbitary structure)

While i am reading Descriptive complexity of #P functions (Saluja) in theorem 1 he state that #FO coincides #P on ordered structures. This is a corollary from fagin’s theorem. I have read fagin’s ...
Omid Yaghoubi's user avatar
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Complexity of sampling a clique uniformly at random

Let $G$ be an undirected graph, and let $C_1, ..., C_M$ denote all possible cliques in $G$. What is known on the complexity of sampling a clique uniformly at random. That is, returning clique $C_i$ ...
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$\mathsf{coNP}^{\mathsf{\#P}}$ and $\mathsf{coNP}^{\mathsf{\#P}^\mathsf{\#P}}$

I was reading a paper that demonstrates that deciding whether a loop-free program is $\varepsilon$-differentially private is $\mathsf{coNP}^{\mathsf{\#P}}$-complete. What are some other problems that ...
Glycerius's user avatar
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Complexity of the unique homomorphism problem up to automorphisms

I am interested in the following problem: given two relational structures $\mathbf{A},\mathbf{B}$, is there a unique homomorphism from $\mathbf{A}$ to $\mathbf{B}$ up to automorphisms of $\mathbf{B}$, ...
Rémi's user avatar
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Number of equivalent formulas in a function-free first order logic language?

In this paper by Martin Grohe, in the first paragraph of section 4.1, it says: "because upto logical equivalence there only exist finitely many $FO[\rho]$ formulas of quantifier rank at most $q$ ...
SagarM's user avatar
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Problems in $P^{PP}$

I just discovered that a problem that I was studying could belong to $P^{PP}$, I would like to prove that this problem is $P^{PP}$-complete (if that is even a thing). The issue is that I'm unable to ...
AITOR GODOY's user avatar
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Question about #P-completeness and NP-completeness

In the book Nature of Computation by Moore & Mertens there is an exercise saying "show that if a counting problem #A is #P-complete with respect to parsimonious reductions, that is if every ...
ddr's user avatar
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Power of unique counting class

One question that recently encountered is the following, suppose I have a task $L$ which has input length $n$, the problem is in the $\text{NP}$ and I promise that there is a unique solution. (The ...
En-Jui Kuo's user avatar
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On the proof of $PP = P \iff \#P = FP$ in Arora & Barak (Lemma 17.7)

Introduction I am currently studying chapter 17 (of the famous textbook by Arora & Barak [1]) on the complexity of counting and got stuck on the proof of Lemma 17.7, which states $\mathrm{PP} = \...
sebastian's user avatar
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Approximate inclusion-Exclusion?

I am trying to understand or find literature on the following problem of approximate inclusion exclusion. Let $S:=\{A_i\}_{i=1}^{m}$ be a set of $m$ sets. Every intersection of $k$ elements in $S$ ...
SagarM's user avatar
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Growth rate of Knapsack Solutions

Let's say I have a Knapsack with capacity $\tau$, and I have an infinite sequence of items with weights $(a_n)_{n=1}^{\infty}$. A feasible Knapsack solution is a subset $S \subset \mathbb{N}$ such ...
Asterix's user avatar
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Reducing counting minimal vertex covers to counting minimum cardinality vertex covers

Consider two problems. Problem 1: Given a graph $G = (V, E)$, find the number of minimum cardinality vertex covers of $G$. Problem 2: Given a graph $G = (V, E)$, find the number of minimal vertex ...
AngryLion's user avatar
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$\#NAE2SAT$ and $\oplus NAE2SAT$ complexity

Deciding $2SAT$ is in $NL$ and $\#2SAT$ is $\#P$ complete while $\oplus2SAT$ is $\oplus P$ complete. Deciding $SAT$-$2$-$NAE$ - every clause has exactly $2$ literals, is there an $NAE$ satisfying ...
Turbo's user avatar
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Complexity of projected model counting

Counting the models of propositional quantifier-free formulas, #SAT, is #P-complete (under parsimonious reductions). I was wondering about the complexity of counting the models of existentially ...
David Monniaux's user avatar
6 votes
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What is known about $\mathrm{NP}^{\mathrm{PP}[1]}$?

Following early discussion on Complexity of maximizing the number of models in a parametric formula it seems that the problem discussed is equivalent to a complete problem in $\mathrm{NP}^{\mathrm{PP}[...
David Monniaux's user avatar
6 votes
1 answer
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Complexity of maximizing the number of models in a parametric formula

Let $F(x,y)$ be a propositional formula where $x$ and $y$ are vectors of Booleans. We want to maximize over $x$ the number of models of $F$ over $y$. As a decision problem, this becomes: given $F(x,y)$...
David Monniaux's user avatar
5 votes
1 answer
190 views

Hashing-based vs almost uniform sampling-based approximate counting

Corollary 3.6 in the UniqueSAT paper by Valiant and Vazirani [1] states: For any $\varepsilon > 0$ there is a randomized polynomial-time TM with a SAT oracle, which given a SAT formula $f$ outputs ...
delete000's user avatar
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10 votes
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Fastest Known Algorithm to Count Acyclic Orientations in a Graph

Given an undirected graph $G$, an acyclic orientation of $G$ is choice of orientation for each edge of $G$ (turning each edge into an arc) such that the resulting directed graph has no directed cycles....
Naysh's user avatar
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$\#$P hardness of computing weighted sum of degree $2$ polynomials

Consider polynomials $f: \{0, 1\}^{n} \rightarrow \{0, 1\}$ over $\mathbb{F}_2$ (addition and multiplication are taken modulo $2$.) Consider integers $x \in \{0,1\}^{n}$, written in binary. Let $\...
AngryLion's user avatar
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Relative error estimation of a special type of GapP function

Consider the functions included in the complexity class GapP. We know that approximating a function from GapP, in the worst case, to inverse polynomial multiplicative error, is #P-hard. Even correctly ...
AngryLion's user avatar
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Complexity of counting 3-colourings of planar bounded degree graphs

The following are known: It is #P-complete to count the number of 3-colourings of a planar graph (with respect to randomized reductions) [1]. For all $d\geq 3$, it is #P-complete to count the number ...
Cyriac Antony's user avatar
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The complexity of tensor formula evaluation problem over an infinite field

In the paper The complexity of tensor calculus by C. Damm, M. Holzer and P. McKenzie (link), the authors reduced the problem of computing the permanent of 0/1-matrices to that of evaluating tensor ...
Conn-CaoYK's user avatar
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Additive error approximations of GapP functions

Consider a GapP function $g(x)$ for $x \in \{0, 1\}^{*}$. Consider an approximation $\tilde g(x)$ such that \begin{equation} \left|g(x) - \tilde g(x)\right| \leq \epsilon. \end{equation} Consider a ...
AngryLion's user avatar
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Improving the approximation in Stockmeyer's counting theorem

Given a $\#P$ function $f(x)$, we can use Stockmeyer's counting theorem to get an approximation $g(x)$ such that \begin{equation} \left(1 - \frac{1}{\text{poly}(n)} \right) f(x) \le g(x) \le \left(...
AngryLion's user avatar
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$CH=UL$ and partial breaking of transitive closure bottleneck problem and Savitch's theorem?

Let $L^t=DSPACE[O(\log n)^t]$, $NL^t=NSPACE[O(\log n)^t]$ and $UL^t=USPACE[O(\log n)^t$. Savitch provides $NL\subseteq L^{2}$. If $CH=UL$ we clearly got rid of the transitive closure bottleneck ...
Turbo's user avatar
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8 votes
2 answers
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Are there analogous works to PPSZ algorithm for #P?

The PPSZ algorithm tells us that we can do SAT-solving for $k-$CNF in time at-most $2^{1-(1-o(1))\frac{\pi^2}{6k}}$. My question is that do we know such results for counting problems in class #P too ? ...
SagarM's user avatar
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Knowing if there are two solutions to the subset sum problem

I was wondering if there are any results that say how hard it is to answer the question are there TWO subsets that sum to a fixed value? In other words, the subset sum problem but asking if there are ...
user73236's user avatar
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Counting subsets of bipartite graph part which admit an induced perfect matching

Given a bipartite graph $G=(U \sqcup V, E)$, count $U^\prime \subseteq U$ for which $\exists V^\prime \subseteq V$ such that the induced subgraph $G[U^\prime \sqcup V^\prime]$ contains a perfect ...
Colin McDonagh's user avatar
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0 answers
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Approximate counting with non-uniform sampler

Suppose we have a predicate $\phi:\{0,1\}^n\to \{0, 1\}$ corresponding to a self-reducible problem and a FPAUS that can approximately sample from a distribution $p$ such that $\|p-u\|_{L_1}\leq \delta$...
Nocturne's user avatar
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How does complexity of a counting problem influence wether it admits a closed form formula or not?

In https://arxiv.org/abs/1412.1505, the section "Results on Data Complexity" mentions the fact that since the authors are about to proove $\#P_1$ complexity for weighted model counting in ...
SagarM's user avatar
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Is there an oracle that separates $PH$ from counting classes?

Is there an oracle $A$ for which $P^A =PH^A \neq CH^A = NEXP^A$ holds?
Turbo's user avatar
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13 votes
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Why is the reduction from 3-SAT to 3-dimensional Matching Parsimonious?

In this talk at the Simons Institute, Holger Dell notes that there is a parsimonious reduction from 3-SAT to the 3-dimensional Matching (3-DM) problem. In other words, there is a reduction between ...
Naysh's user avatar
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1 vote
1 answer
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Consequences of turning $\oplus \text{SAT}$ into few satisfying assignments

Suppose there is a reduction which, given a $\oplus \text{SAT}$ instance $\phi$, returns another $\oplus \text{SAT}$ instance $\psi$ having all the following properties: The size of $\psi$ is ...
Giorgio Camerani's user avatar
4 votes
0 answers
207 views

On solving Planar Circuit SAT

This enquiry is three-sided. Side 1 - State of the art Which is the best known algorithm for $\text{PLANAR-CIRCUIT-SAT}$? Which is the best known algorithm for $\text{PLANAR-CIRCUIT-SAT}$ assuming ...
Giorgio Camerani's user avatar
1 vote
0 answers
236 views

Disproving $\oplus$ETH by reducing $\oplus k$-SAT with $n$ variables and $m$ clauses to planar graph with $o(m^2)$ vertices?

In this question and its answer, they discuss about reducing CNF-SAT with $n$ variables and $m$ clauses to a (problem on) planar graph $G=(V,E)$ with $|V|$ as small as possible. It is said that the ...
Giorgio Camerani's user avatar
6 votes
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Counting on grid graphs

Are there problems defined on graphs, such as counting 2-factors, Hamiltonian cycles, connected spanning subgraphs etc., that are in $\#P$ and remain hard for grid graphs? Since there seem to be ...
delete000's user avatar
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The Edge Cover Equilibrium Problem

Let the Edge Cover Equilibrium Problem be the following: INPUT: a simple undirected graph $G$. OUTPUT: YES, if the number of edge covers of $G$ having odd cardinality is equal to the number of edge ...
Giorgio Camerani's user avatar
1 vote
2 answers
190 views

Complexity of Model Enumeration in function free, equality free, First Order Logic with only Unary Predicates?

This question has inspired the following two questions. Given a first order logic language, with only unary predicates, finite number of variables, $\forall$ and $\exists$ i.e no equality and ...
SagarM's user avatar
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1 answer
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What evidences are there that $PP$ is in $BQP$ and $PP$ is not in $BQP$?

Unlike hierarchy collapse arguments for classical complexity we have that quantum complexity is different. What evidences are there that $PP$ is in $BQP$? What evidences are there that $PP$ is not ...
Turbo's user avatar
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1 vote
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Constructing FOL formula for which counting is easy?

Given a function free First Order Logic language $\mathcal{L}$ are there ways to write formulas for which counting the number of models for a given cardinality of the domain is easy (preferably exists ...
SagarM's user avatar
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-4 votes
1 answer
406 views

does within the "range a and b" include a and b?

I have not found the answer to this doubt of mine elsewhere, hence posting it here. It may be a silly question but I just want to be sure :P would be great if someone could help me out with this ...
dagwood's user avatar
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1 vote
2 answers
144 views

Asymptotic Approximation to Number of Knapsack Solutions

Is there an asymptotic approximation to the fraction of sets satisfying a knapsack feasibility constraint? More precisely, imagine I have a large number $n$ of items with bounded weights $X_1,...,X_n ...
Asterix's user avatar
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