Processing disjunctions in temporal constraint networks

Processing Disjunctions in Temporal Constraint Networks

The framework of Temporal constraint Satisfaction Problems (TCSP) has been proposed for representing and processing temporal knowledge. Deciding consistency of TCSPs is known to be intractable. As demonstrates in this paper, even local consistency algorithms like path-consistency can be exponential due to the fragmentation problem. We present two new polynomial approximation algorithms, Upper-L...

Processing Temporal Constraint Networks

This paper describes new algorithms for processing quantitative and qualitative Temporal Constraint Satisfaction Problems (TCSP). In contrast to discrete Constraint Satisfaction Problems (CSP), enforcing path-consistency on quantitative TCSP is exponential, due to the fragmentation problem. Identifying the fragmentation problem allows us to design several e cient polynomial algorithms that are ...

Coping With Disjunctions in Temporal Constraint Satisfaction Problems

Path-consistency algorithms, which are polynomial for discrete problems, are exponential when applied to problems involving quantitative temporal information. The source of complexity stems from specifying relationships between pairs of time points as disjunction of intervals. We propose a polynomial algorithm, called ULT, that approximates path-consistency in Temporal Constraint Satisfaction P...

Temporal Constraint Networks

Temporal Constraint Networks in Action

This paper presents an integration of the well known Temporal Constraint Networks representation into a causal approach for reasoning about actions calledAL2 [9]. As a result, temporal constraints are allowed in the conditions of the causal rules that describe the domain behavior. We show the adequacy of the AL2 understanding of causation (based on the concept of pertinence) for naturally intro...