# Toward an automaton Constraint for Local Search

## TL;DR

This paper introduces a novel automaton-based constraint for local search, enabling incremental violation tracking and demonstrating practical effectiveness in personnel rostering problems.

## Contribution

It presents a new automaton constraint for local search that maintains violations incrementally, improving constraint handling efficiency.

## Key findings

- Automaton constraints are practical for real-life personnel rostering.
- The approach is competitive with existing methods.
- Incremental violation maintenance enhances local search performance.

## Abstract

We explore the idea of using finite automata to implement new constraints for local search (this is already a successful technique in constraint-based global search). We show how it is possible to maintain incrementally the violations of a constraint and its decision variables from an automaton that describes a ground checker for that constraint. We establish the practicality of our approach idea on real-life personnel rostering problems, and show that it is competitive with the approach of [Pralong, 2007].