64 research outputs found
On the Problem of Computing the Probability of Regular Sets of Trees
We consider the problem of computing the probability of regular languages of
infinite trees with respect to the natural coin-flipping measure. We propose an
algorithm which computes the probability of languages recognizable by
\emph{game automata}. In particular this algorithm is applicable to all
deterministic automata. We then use the algorithm to prove through examples
three properties of measure: (1) there exist regular sets having irrational
probability, (2) there exist comeager regular sets having probability and
(3) the probability of \emph{game languages} , from automata theory,
is if is odd and is otherwise
A weakness measure for GR(1) formulae
In spite of the theoretical and algorithmic developments for system synthesis in recent years, little effort has been dedicated to quantifying the quality of the specifications used for synthesis. When dealing with unrealizable specifications, finding the weakest environment assumptions that would ensure realizability is typically a desirable property; in such context the weakness of the assumptions is a major quality parameter. The question of whether one assumption is weaker than another is commonly interpreted using implication or, equivalently, language inclusion. However, this interpretation does not provide any further insight into the weakness of assumptions when implication does not hold. To our knowledge, the only measure that is capable of comparing two formulae in this case is entropy, but even it fails to provide a sufficiently refined notion of weakness in case of GR(1) formulae, a subset of linear temporal logic formulae which is of particular interest in controller synthesis. In this paper we propose a more refined measure of weakness based on the Hausdorff dimension, a concept that captures the notion of size of the omega-language satisfying a linear temporal logic formula. We identify the conditions under which this measure is guaranteed to distinguish between weaker and stronger GR(1) formulae. We evaluate our proposed weakness measure in the context of computing GR(1) assumptions refinements
06051 Abstracts Collection -- Kolmogorov Complexity and Applications
From 29.01.06 to 03.02.06, the Dagstuhl Seminar 06051 ``Kolmogorov Complexity and Applications\u27\u27 was held in the International Conference and Research Center (IBFI),
Schloss Dagstuhl. During the seminar, several participants presented
their current research, and ongoing work and open problems were
discussed. Abstracts of the presentations given during the seminar
as well as abstracts of seminar results and ideas are put together
in this paper. The first section describes the seminar topics and
goals in general. Links to extended abstracts or full papers are
provided, if available
Lipschitz Robustness of Finite-state Transducers
We investigate the problem of checking if a finite-state transducer is robust
to uncertainty in its input. Our notion of robustness is based on the analytic
notion of Lipschitz continuity --- a transducer is K-(Lipschitz) robust if the
perturbation in its output is at most K times the perturbation in its input. We
quantify input and output perturbation using similarity functions. We show that
K-robustness is undecidable even for deterministic transducers. We identify a
class of functional transducers, which admits a polynomial time
automata-theoretic decision procedure for K-robustness. This class includes
Mealy machines and functional letter-to-letter transducers. We also study
K-robustness of nondeterministic transducers. Since a nondeterministic
transducer generates a set of output words for each input word, we quantify
output perturbation using set-similarity functions. We show that K-robustness
of nondeterministic transducers is undecidable, even for letter-to-letter
transducers. We identify a class of set-similarity functions which admit
decidable K-robustness of letter-to-letter transducers.Comment: In FSTTCS 201
Computing Measures of Weak-MSO Definable Sets of Trees
This work addresses the problem of computing measures of recognisable sets of infinite trees. An algorithm is provided to compute the probability measure of a tree language recognisable by a weak alternating automaton, or equivalently definable in weak monadic second-order logic. The measure is the uniform coin-flipping measure or more generally it is generated by a branching stochastic process. The class of tree languages in consideration, although smaller than all regular tree languages, comprises in particular the languages definable in the alternation-free ?-calculus or in temporal logic CTL. Thus, the new algorithm may enhance the toolbox of probabilistic model checking
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