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 …

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 …

How Random CSPs Fool Hierarchies

SO Chan, HT Ng, S Peng - Proceedings of the 56th Annual ACM …, 2024 - dl.acm.org
Relaxations for the constraint satisfaction problem (CSP) include bounded width, linear
program (LP), semidefinite program (SDP), affine integer program (AIP), and the combined …

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 …

[PDF][PDF] Semidefinite programming and linear equations vs. homomorphism problems

L Ciardo, S Živný - Proceedings of the 56th Annual ACM Symposium on …, 2024 - dl.acm.org
We introduce a relaxation for homomorphism problems that combines semidefinite
programming with linear Diophantine equations, and propose a framework for the analysis …

On the complexity of the approximate hypergraph homomorphism problem

L Ciardo, M Kozik, A Krokhin, TV Nakajima… - arXiv preprint arXiv …, 2023 - arxiv.org
Understanding the computational complexity of fragments of the Constraint Satisfaction
Problem (CSP) has been instrumental in the formulation of Feder-Vardi's Dichotomy …

The Sherali-Adams and Weisfeiler-Leman hierarchies in (Promise Valued) Constraint Satisfaction Problems

L Barto, S Butti, V Dalmau - arXiv preprint arXiv:2401.16998, 2024 - arxiv.org
In this paper we study the interactions between so-called fractional relaxations of the integer
programs (IPs) which encode homomorphism and isomorphism of relational structures. We …

Promise and Infinite-Domain Constraint Satisfaction

A Mottet - 32nd EACSL Annual Conference on Computer …, 2024 - drops.dagstuhl.de
Two particularly active branches of research in constraint satisfaction are the study of
promise constraint satisfaction problems (PCSPs) with finite templates and the study of …

Quantum advantage and CSP complexity

L Ciardo - arXiv preprint arXiv:2404.13186, 2024 - arxiv.org
Information-processing tasks modelled by homomorphisms between relational structures
can witness quantum advantage when entanglement is used as a computational resource …

The periodic structure of local consistency

L Ciardo, S Živný - arXiv preprint arXiv:2406.19685, 2024 - arxiv.org
We connect the mixing behaviour of random walks over a graph to the power of the local-
consistency algorithm for the solution of the corresponding constraint satisfaction problem …