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# Questions tagged [satisfiability]

Satisfiability (SAT) is the problem of determining whether there is a variable assignment that fulfills a given Boolean formula.

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### Complexity of a variant of #Positive-2-SAT

#Positive-2SAT is the problem of counting the number of satisfying assignments to a given Positive 2-CNF formula i.e 2-CNF formulas in which each literal is a positive occurrence of a variable. The ...
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### Counting number of assignments restricted by implications

Suppose we have $n$ boolean variables, $x_1, \dots, x_n$. Some boolean variables can have implication relationships, e.g. $x_2 \implies x_5$, which means that if $x_2$ is true $x_5$ must also be true. ...
1 vote
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### Best compression algorithm for CNF SAT instances in DIMACS

For a CNF SAT instance in the DIMACS format what is the best algorithm to compress it? What is the best algorithm for 3-SAT instances in particular? In 2020 SAT competition used .xz which if I ...
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### Minimum unsat core and generalization

I have a problem that has been in my head for some time, it might be already well known but i cannot find ressources on something similar : The idea came from the will to identify the minimal unsat ...
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### Is 3, 3 satisfiability trivial after all?

Tovey's paper from 1982 clearly states that: Theorem 2.1. Boolean satisfiability is NP-complete when restricted to instances with 2 or 3 variables per clause and at most 3 occurrences per variable. ...
1 vote
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### Do stably-infinite theories exclude finite sorts?

Nelson-Oppen requires theories to be stably infinite. Meaning, that each theory allows extending models to have an infinite domain. A commonly mentioned counter example is that the theory of bit ...
1 vote
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### Is stable infinity required of theories combined with model-based theory combination?

In the paper "Model-Based Theory Combination" (1) by De Moura and Bjorner they present an alternative to the Nelson-Oppen method for theory combination. They first describe the Nelson-Oppen ...
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1 vote
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### Is there an SMT/SAT algorithm for General Predicate Logic (FOL)?

I'm learning how to write my own theorem prover. After skimming Decision Procedures (Kroening & Strichman, 2016), I didn't find any SMT algorithms for solving quantified n-ary predicate formulas. ...
1 vote
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### "package" compatibility solver with verion ranges

I am looking for how to solve the package compatibility problem. I have found some relevant research and libraries. But some of them are older. I am wondering if there is any more recent research and ...
1 vote
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### A Fast Linear-Arithmetic Solver: How can Gaussian elimination be used to simplify matrix A?

I am working on an LRA Theory solver for SymPy, an open source python library for symbolic computations. You can find my work here. Currently I'm trying to optimize it to run faster. My implementation ...
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### Is it an open problem if CDCL algorithms violate SETH?

Strong Exponential Time Hypothesis states that general SAT, where clauses are not limited in length, can't be solved in time $o(2^n)$. It's proven that DPLL algorithm requires $\Omega(2^n)$ time in ...
1 vote
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### Is there a linear programming method that is polynomial in the number of variables, constraints and bitlength of numbers?

AFAIK, Interior Point method for solving a system of linear inequations is polynomial in the number of variables and constraints. Probably there are others. I don't need to optimize any function (...
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### Satisfiability of a boolean formula with two occurrences of each variable with a special ordering

I am interested in the complexity of a special case of the boolean satisfiability problem: We are given a boolean formula, consisting only of the logical operators $\land$ and $\lor$ (that can be ...
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### Restriction of SAT to CNF

I have spent a lot of time understanding these two issues. If you can help me, please. Prove that the restriction of SAT to CNF formulas in which each variable xi appears at most twice is solvable in ...
1 vote
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### how to polynomially check if a given boolean formula is unsatisfiable

Since SAT is np-complete, there is a polynomial algorithm to check if a given solution for any particular formula is correct. Just substitute the values and solve. But what if one claims that the ...
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### Tseitin formula on 2-connected graph

How can we prove that for $\\\\$ every $\\\\$ 2-connected graph G with an odd number of vertices, the unsatisfiable Tseitin formula for it is minimally unsatisfiable, that is, if we remove even a ...
1 vote
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### Monotone boolean satisfiability problem : finding minimal solutions

I am very interested in the following questions, which sprang out from the topological study of loops in surfaces and their intersection numbers. Consider, over a finite set of boolean variables $X$, ...
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### SAT formulation of the condition that an even number of a given set of variables must be set to true

Lets say I have a SAT problem with variables $x_1,...,x_n$. For a given subset of the variables I want to create a clause which forces an even number of the variables in $S$ to be true. Of course ...
1 vote
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### How to find the learned clause from a UIP cut

I would guess that this question is going to make some people wonder how I haven't already found a solution looking through papers -- but I do not see a clear algorithm. In implementing CDCL, I read ...
1 vote
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### Is it possible to find reductions from problems in $\mathsf{NP}$ to SAT based solely on the certificate verification algorithm?

The following problem has made me ask this question: Given a boolean formula $\varphi(X)$ decide if there exists a quantification of $\varphi(X)$ with $k$ $\forall$ quantifiers that holds true. ...
1 vote
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### CNF Horn-renamability to 3-CNF Horn-renamability reduction?

A CNF formula is Horn-renamable if you can invert variables in such a way that each clause has at most one positive literal. There is an algorithm based on a reduction to 2-SAT given in Renaming a Set ...
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### Is it possible to reduce functional equations to SAT?

The problem of finding a solution for functional equations can be defined as: Let $A_0, A_1, A_2, \dots, A_n, B_0, B_1, B_2, \dots, B_n, X$ be terms of the $\lambda$-calculus, where all terms are ...
1 vote
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### Reduce CNF-SAT to decision problem

Given CNF-SAT reduce it to the following decision problem: Given n items, m groups (and for each group a set of items) and a ...
### Does $\mathsf{NC_1\subsetneq NC}$ imply $\mathsf{NP\neq coNP}$?
Any $\mathsf{NC}$ circuit could be presented in SAT form via Tseytin transform. This applies in the reverse too: an arbitrary SAT instance could encode any $\mathsf{NC}$ circuit. Now, Frege proof ...