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2016 | OriginalPaper | Buchkapitel

Solving and Verifying the Boolean Pythagorean Triples Problem via Cube-and-Conquer

verfasst von : Marijn J. H. Heule, Oliver Kullmann, Victor W. Marek

Erschienen in: Theory and Applications of Satisfiability Testing – SAT 2016

Verlag: Springer International Publishing

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Abstract

The boolean Pythagorean Triples problem has been a longstanding open problem in Ramsey Theory: Can the set \(\mathbb {N}= \{1,2,\dots \}\) of natural numbers be divided into two parts, such that no part contains a triple (abc) with \(a^2 + b^2 = c^2\) ? A prize for the solution was offered by Ronald Graham over two decades ago. We solve this problem, proving in fact the impossibility, by using the Cube-and-Conquer paradigm, a hybrid SAT method for hard problems, employing both look-ahead and CDCL solvers. An important role is played by dedicated look-ahead heuristics, which indeed allowed to solve the problem on a cluster with 800 cores in about 2 days. Due to the general interest in this mathematical problem, our result requires a formal proof. Exploiting recent progress in unsatisfiability proofs of SAT solvers, we produced and verified a proof in the DRAT format, which is almost 200 terabytes in size. From this we extracted and made available a compressed certificate of 68 gigabytes, that allows anyone to reconstruct the DRAT proof for checking.

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Fußnoten
1
In practice this is done using a single incremental CNF file. For details about the format, see http://​www.​siert.​nl/​icnf/​.
 
2
 
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Metadaten
Titel
Solving and Verifying the Boolean Pythagorean Triples Problem via Cube-and-Conquer
verfasst von
Marijn J. H. Heule
Oliver Kullmann
Victor W. Marek
Copyright-Jahr
2016
DOI
https://doi.org/10.1007/978-3-319-40970-2_15