---
title: "Cooperative Search and Nogood Recording"
authors:
  - "Cyril Terrioux"
doi: ""
url: "https://ijcai.org/proceedings/2001/37"
pdf: "https://ijcai.org/proceedings/2001/0037.pdf"
venue: "Proceedings of the Seventeenth International Joint Conference on Artificial Intelligence"
year: 2001
pages: "260-264"
track: ""
keywords:
---

# Cooperative Search and Nogood Recording

Cyril Terrioux

*Proceedings of the Seventeenth International Joint Conference on Artificial Intelligence*, pages 260-264.

## Abstract

Within the framework of constraint satisfaction problem, we propose a new scheme of cooperative parallel search. The cooperation is realized by exchanging nogoods (instantiations which can’t be extended to a solution). We associate a process with each solver and we introduce a manager of nogoods, in order to regulate exchanges of nogoods. Each solver runs the algorithm Forward-Checking with Nogood Recording. We add to algorithm a phase of interpretation, which limits the size of the search tree according to the received nogoods. Solvers differ from each other in ordering variables and/or values by using different heuristics. The interest of our approach is shown experimentally. In particular, we obtain linear or superlinear speed-up for consistent problems, like for inconsistent ones, up to about ten solvers.