Half-checking propagators

by   Mikael Zayenz Lagerkvist, et al.

Propagators are central to the success of constraint programming, that is contracting functions removing values proven not to be in any solution of a given constraint. The literature contains numerous propagation algorithms, for many different constraints, and common to all these propagation algorithms is the notion of correctness: only values that appear in no solution to the respective constraint may be removed. In this paper half-checking propagators are introduced, for which the only requirements are that identified solutions (by the propagators) are actual solutions (to the corresponding constraints), and that the propagators are contracting. In particular, a half-checking propagator may remove solutions resulting in an incomplete solving process, but with the upside that (good) solutions may be found faster. Overall completeness can be obtained by running half-checking propagators as one component in a portfolio solving process. Half-checking propagators opens up a wider variety of techniques to be used when designing propagation algorithms, compared to what is currently available. A formal model for half-checking propagators is introduced, together with a detailed description of how to support such propagators in a constraint programming system. Three general directions for creating half-checking propagation algorithms are introduced, and used for designing new half-checking propagators for the cost-circuit constraint as examples. The new propagators are implemented in the Gecode system.


page 1

page 2

page 3

page 4


Generalized Support and Formal Development of Constraint Propagators

Constraint programming is a family of techniques for solving combinatori...

Using Description Logics for RDF Constraint Checking and Closed-World Recognition

RDF and Description Logics work in an open-world setting where absence o...

A Theoretical Study of (Full) Tabled Constraint Logic Programming

Logic programming with tabling and constraints (TCLP, tabled constraint ...

Some Remarks on Boolean Constraint Propagation

We study here the well-known propagation rules for Boolean constraints. ...

Conformance checking: A state-of-the-art literature review

Conformance checking is a set of process mining functions that compare p...

A Proof Theoretic View of Constraint Programming

We provide here a proof theoretic account of constraint programming that...

Reliability of Checking an Answer Given by a Mathematical Expression in Interactive Learning Systems

In this article we address the problem of automatic answer checking in i...

Please sign up or login with your details

Forgot password? Click here to reset