,
Lutz Schröder
,
Paul Wild
,
Barbara König
,
Pedro Nora
Creative Commons Attribution 4.0 International license
Behavioural distances generally offer more fine-grained means of comparing quantitative systems than two-valued behavioural equivalences. They often relate to quantitative modal logics that characterize a given behavioural distance in terms of the induced logical distance. We develop a unified framework for behavioural distances and logics induced by a special type of modalities that lift two-valued predicates to quantitative predicates. A typical example is the probability operator, which maps a two-valued predicate A to a quantitative predicate on probability distributions assigning to each distribution the respective probability of A. Correspondingly, the prototypical example of our framework is ε-bisimulation distance of Markov chains, which has recently been shown to coincide with the behavioural distance induced by the popular Lévy-Prokhorov distance on distributions. Other examples include behavioural distance on metric transition systems and Hausdorff behavioural distance on fuzzy transition systems. We establish a number of general results in this framework, including existence and polynomial-time computation of distinguishing formulae in two characteristic modal logics: A two-valued logic with a notion of satisfaction up to ε, and a quantitative logic. These general results instantiate to new results in many of the mentioned examples. Notably, we obtain polynomial-time computation of distinguishing formulae for ε-bisimulation distance of Markov chains in a quantitative logic featuring a "generally" modality used in probabilistic knowledge representation.
@InProceedings{forster_et_al:LIPIcs.CONCUR.2026.35,
author = {Forster, Jonas and Schr\"{o}der, Lutz and Wild, Paul and K\"{o}nig, Barbara and Nora, Pedro},
title = {{Threshold-Based Behavioural Distances}},
booktitle = {37th International Conference on Concurrency Theory (CONCUR 2026)},
pages = {35:1--35:19},
series = {Leibniz International Proceedings in Informatics (LIPIcs)},
ISBN = {978-3-95977-447-5},
ISSN = {1868-8969},
year = {2026},
volume = {391},
editor = {Sokolova, Ana and Totzke, Patrick},
publisher = {Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
address = {Dagstuhl, Germany},
URL = {https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.CONCUR.2026.35},
URN = {urn:nbn:de:0030-drops-273657},
doi = {10.4230/LIPIcs.CONCUR.2026.35},
annote = {Keywords: Behavioural distance, modal logic, quantitative logic, coalgebra, Sugeno integration}
}