4 results
Vojtěch Forejt ; Petr Jančar ; Stefan Kiefer ; James Worrell.
We study the bisimilarity problem for probabilistic pushdown automata (pPDA) and subclasses thereof. Our definition of pPDA allows both probabilistic and non-deterministic branching, generalising the classical notion of pushdown automata (without epsilon-transitions). We first show a general […]
Published on November 15, 2018
Stefan Kiefer ; Ines Marusic ; James Worrell.
We consider the problem of minimising the number of states in a multiplicity tree automaton over the field of rational numbers. We give a minimisation algorithm that runs in polynomial time assuming unit-cost arithmetic. We also show that a polynomial bound in the standard Turing model would require […]
Published on March 28, 2017
Nathanaël Fijalkow ; Stefan Kiefer ; Mahsa Shirmohammadi.
Given two labelled Markov decision processes (MDPs), the trace-refinement problem asks whether for all strategies of the first MDP there exists a strategy of the second MDP such that the induced labelled Markov chains are trace-equivalent. We show that this problem is decidable in polynomial time if […]
Published on June 3, 2020
Dmitry Chistikov ; Stefan Kiefer ; Andrzej S. Murawski ; David Purser.
Given two weighted automata, we consider the problem of whether one is big-O of the other, i.e., if the weight of every finite word in the first is not greater than some constant multiple of the weight in the second. We show that the problem is undecidable, even for the instantiation of weighted […]
Published on March 15, 2022