,
Stefan Schupp
,
Gerhard Lakemeyer
Creative Commons Attribution 4.0 International license
Representing time is crucial for cyber-physical systems and has been studied extensively in the situation calculus. The most commonly used approach represents time by adding a real-valued function time(a) that attaches a time point to each action and consequently to each situation. We show that in this approach, checking whether there is a reachable situation that satisfies a given formula is undecidable, even when the domain contains only finitely many objects. We present an alternative approach based on well-established results from timed automata theory by introducing clocks as real-valued fluents with restricted successor state axioms and comparison operators. With this restriction, we can show that the reachability problem for finite-domain basic action theories is decidable. Finally, we apply our results to Golog program realization by presenting a decidable procedure for determining an action sequence that is a successful execution of a given program.
@InProceedings{hofmann_et_al:OASIcs.TIME.2026.11,
author = {Hofmann, Till and Schupp, Stefan and Lakemeyer, Gerhard},
title = {{Decidable Reasoning About Time in Finite-Domain Situation Calculus Theories}},
booktitle = {33rd International Symposium on Temporal Representation and Reasoning (TIME 2026)},
pages = {11:1--11:22},
series = {Open Access Series in Informatics (OASIcs)},
ISBN = {978-3-95977-448-2},
ISSN = {2190-6807},
year = {2026},
volume = {146},
editor = {Orlandini, AndreA and Pinchinat, Sophie},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.TIME.2026.11},
URN = {urn:nbn:de:0030-drops-277073},
doi = {10.4230/OASIcs.TIME.2026.11},
annote = {Keywords: Situation Calculus, Golog, timed automata, clocks, dense time, reachability, decidability, region abstraction, program realization}
}