Approximate graph colouring and the hollow shadow

L Ciardo, S Živný - Proceedings of the 55th Annual ACM Symposium on …, 2023 - dl.acm.org
We show that approximate graph colouring is not solved by constantly many levels of the lift-
and-project hierarchy for the combined basic linear programming and affine integer …

CLAP: A new algorithm for promise CSPs

L Ciardo, S Živný - SIAM Journal on Computing, 2023 - SIAM
We propose a new algorithm for Promise Constraint Satisfaction Problems (PCSPs). It is a
combination of the Constraint Basic LP relaxation and the Affine IP relaxation (CLAP). We …

SDPs and robust satisfiability of promise CSP

J Brakensiek, V Guruswami, S Sandeep - Proceedings of the 55th …, 2023 - dl.acm.org
For a constraint satisfaction problem (CSP), a robust satisfaction algorithm is one that
outputs an assignment satisfying most of the constraints on instances that are near …

Promise constraint satisfaction and width

A Atserias, V Dalmau - Proceedings of the 2022 Annual ACM-SIAM …, 2022 - SIAM
We study the power of the bounded-width consistency algorithm in the context of the fixed-
template Promise Constraint Satisfaction Problem (PCSP). Our main technical finding is that …

Approximate graph colouring and crystals

L Ciardo, S Živný - Proceedings of the 2023 Annual ACM-SIAM …, 2023 - SIAM
We show that approximate graph colouring is not solved by any level of the affine integer
programming (AIP) hierarchy. To establish the result, we translate the problem of exhibiting …

Hierarchies of minion tests for PCSPs through tensors

L Ciardo, S Živný - Proceedings of the 2023 Annual ACM-SIAM …, 2023 - SIAM
We provide a unified framework to study hierarchies of relaxations for Constraint Satisfaction
Problems and their Promise variant. The idea is to split the description of a hierarchy into an …

An invitation to the promise constraint satisfaction problem

A Krokhin, J Opršal - ACM SIGLOG News, 2022 - dl.acm.org
The study of the complexity of the constraint satisfaction problem (CSP), centred around the
Feder-Vardi Dichotomy Conjecture, has been very prominent in the last two decades. After a …

Promise constraint satisfaction: Algebraic structure and a symmetric boolean dichotomy

J Brakensiek, V Guruswami - SIAM Journal on Computing, 2021 - SIAM
A classic result due to Schaefer Proceedings of STOC 78, ACM, 1978, pp. 216--226
classifies all constraint satisfaction problems (CSPs) over the Boolean domain as being …

Solving promise equations over monoids and groups

A Larrauri, S Živný - ACM Transactions on Computational Logic, 2024 - dl.acm.org
We give a complete complexity classification for the problem of finding a solution to a given
system of equations over a fixed finite monoid, given that a solution over a more restricted …

1-in-3 vs. Not-All-Equal: Dichotomy of a broken promise

L Ciardo, M Kozik, A Krokhin, TV Nakajima… - Proceedings of the 39th …, 2024 - dl.acm.org
The 1-in-3 and Not-All-Eqal satisfiability problems for Boolean CNF formulas are two well-
known NP-hard problems. In contrast, the promise 1-in-3 vs. Not-All-Eqal problem can be …