From local to global consistency in temporal constraint networks

AbstractWe study the problem of global consistency for several classes of quantitative temporal constraints which include inequalities, inequations and disjunctions of inequations. In all cases that we consider we identify the level of local consistency that is necessary and sufficient for achieving global consistency and present an algorithm which achieves this level. As a byproduct of our analysis, we also develop an interesting minimal network algorithm

From Local to Global Consistency in Temporal Constraint Networks

We study the problem of global consistency for several classes of quantitative temporal constraints which include inequalities, inequations and disjunctions of inequations. In all cases that we consider we identify the level of local consistency that is necessary and sufficient for achieving global consistency and present an algorithm which achieves this level. As a byproduct of our analysis, we also develop an interesting minimal network algorithm. 1 Introduction One of the most important notions found in the constraint satisfaction literature is global consistency [Fre78]. In a globally consistent constraint set all interesting constraints are explicitly represented and the projection of the solution set on any subset of the variables can be computed by simply collecting the constraints involving these variables. An important consequence of this property is that a solution can be found by backtrack-free search [Fre82]. Enforcing global consistency can take an exponential amount of ti..