Reducing epsilon-DC Checking for Conditional Simple Temporal Networks to DC Checking

Luke Hunsberger, Roberto Posenato, Michael Wagner
2018 International Symposium/Workshop on Temporal Representation and Reasoning  
Recent work on Conditional Simple Temporal Networks (CSTNs) has introduced the problem of checking the dynamic consistency (DC) property for the case where the reaction time of an execution strategy to observations is bounded below by some fixed > 0, the so-called -DCchecking problem. This paper proves that the -DC-checking problem for CSTNs can be reduced to the standard DC-checking problem for CSTNs -without incurring any computational cost. Given any CSTN S with k observation time-points,
more » ... paper defines a new CSTN S 0 that is the same as S, except that for each observation time-point P ? in S: (i) P ? is demoted to a nonobservation time-point in S 0 ; and (ii) a new observation time-point P 0 ?, constrained to occur exactly units after P ?, is inserted into S 0 . The paper proves that S is -DC if and only if S 0 is (standard) DC, and that the application of the -DC-checking constraint-propagation rules to S is equivalent to the application of the corresponding (standard) DC-checking constraint-propagation rules to S 0 . Two versions of these results are presented that differ only in whether a dynamic strategy for S 0 can react instantaneously to observations, or only after some arbitrarily small, positive delay. Finally, the paper demonstrates empirically that building S 0 and DC-checking it incurs no computational cost as the sizes of the instances increase.
doi:10.4230/lipics.time.2018.15 dblp:conf/time/HunsbergerP18a fatcat:sz3mytzy2zb4zackoegnqlsrx4