Networks

News

Bart Jansen and Astrid Pieterse win Best Paper award at MFCS 2016

Astrid Pieterse

Bart Jansen

Bart Jansen (Assistant Professor) and Astrid Pieterse (PhD student) from the Eindhoven University of               Technology (Algorithms group) won the Best Paper award at the Symposium on Mathematical Foundations of Computer Science (MFCS) 2016 in Krakow, Poland, with their paper ‘Optimal sparsification for some binary CSPs using low-degree polynomials’. They won 300 euro, sponsored by the European Association for Theoretical Computer Science (EATCS).

 

Summary of the research

This paper analyzes to what extent it is possible to efficiently reduce the number of clauses in NP-hard satisfiability problems, without changing the answer. Upper and lower bounds are established using the concept of kernelization. Existing results show that if NP is not contained in coNP/poly, no efficient preprocessing algorithm can reduce n-variable instances of CNF-SAT with d literals per clause, to equivalent instances with O(n^{d-e}) bits for any e > 0. For the Not-All-Equal SAT problem, a compression to size \~O(n^{d-1}) exists. We put these results in a common framework by analyzing the compressibility of binary CSPs. We characterize constraint types based on the minimum degree of multivariate polynomials whose roots correspond to the satisfying assignments, obtaining (nearly) matching upper and lower bounds in several settings. Our lower bounds show that not just the number of constraints, but also the encoding size of individual constraints plays an important role. For example, for Exact Satisfiability with unbounded clause length it is possible to efficiently reduce the number of constraints to n+1, yet no polynomial-time algorithm can reduce to an equivalent instance with O(n^{2-e}) bits for any e > 0, unless NP is a subset of coNP/poly.

 

About the MFCS

The MFCS conference 2016 took place from 22 to 26 August 2016. MFCS conference series is organized since 1972. Traditionally, the conference moved between the Czech Republic, Slovakia, and Poland, while since a few years ago, the conference travels around Europe (in 2013 it was held in Austria, then in 2014 in Hungary, and most recently, in 2015, in Italy). This year the conference visits Poland once again.

MFCS is a high-quality venue for original research in all branches of theoretical computer science. The broad scope of the conference encourages interations between researchers who might not meet at more specialized venues.

The MFCS conference consists of invited lectures and contributed talks, selected by an international program committee of researchers focusing on diverse areas of theoretical computer science.

 

For more information about MFCS visit the website