44 research outputs found
Lazy Probabilistic Model Checking without Determinisation
The bottleneck in the quantitative analysis of Markov chains and Markov
decision processes against specifications given in LTL or as some form of
nondeterministic B\"uchi automata is the inclusion of a determinisation step of
the automaton under consideration. In this paper, we show that full
determinisation can be avoided: subset and breakpoint constructions suffice. We
have implemented our approach---both explicit and symbolic versions---in a
prototype tool. Our experiments show that our prototype can compete with mature
tools like PRISM.Comment: 38 pages. Updated version for introducing the following changes: -
general improvement on paper presentation; - extension of the approach to
avoid full determinisation; - added proofs for such an extension; - added
case studies; - updated old case studies to reflect the added extensio
ISCASMC: A Web-Based Probabilistic Model Checker
We introduce the web-based model checker iscasMc for probabilistic systems (see http://iscasmc.ios.ac.cn/IscasMC). This Java application offers an easy-to-use web interface for the evaluation of Markov chains and decision processes against PCTL and PCTL specifications. Compared to PRISM or MRMC, iscasMc is particularly efficient in evaluating the probabilities of LTL properties. © 2014 Springer International Publishing Switzerland.We introduce the web-based model checker iscasMc for probabilistic systems (see http://iscasmc.ios.ac.cn/IscasMC). This Java application offers an easy-to-use web interface for the evaluation of Markov chains and decision processes against PCTL and PCTL specifications. Compared to PRISM or MRMC, iscasMc is particularly efficient in evaluating the probabilities of LTL properties. © 2014 Springer International Publishing Switzerland
One Theorem to Rule Them All: A Unified Translation of LTL into {\omega}-Automata
We present a unified translation of LTL formulas into deterministic Rabin
automata, limit-deterministic B\"uchi automata, and nondeterministic B\"uchi
automata. The translations yield automata of asymptotically optimal size
(double or single exponential, respectively). All three translations are
derived from one single Master Theorem of purely logical nature. The Master
Theorem decomposes the language of a formula into a positive boolean
combination of languages that can be translated into {\omega}-automata by
elementary means. In particular, Safra's, ranking, and breakpoint constructions
used in other translations are not needed
Statistical language models within the algebra of weighted rational languages
Statistical language models are an important tool in natural language processing. They represent prior knowledge about a certain language which is usually gained from a set of samples called a corpus. In this paper, we present a novel way of creating N-gram language models using weighted finite automata. The construction of these models is formalised within the algebra underlying weighted finite automata and expressed in terms of weighted rational languages and transductions. Besides the algebra we make use of five special constant weighted transductions which rely only on the alphabet and the model parameter N. In addition, we discuss efficient implementations of these transductions in terms of virtual constructions
On the Succinctness of Good-for-MDPs Automata
Good-for-MDPs and good-for-games automata are two recent classes of
nondeterministic automata that reside between general nondeterministic and
deterministic automata. Deterministic automata are good-for-games, and
good-for-games automata are good-for-MDPs, but not vice versa. One of the
question this raises is how these classes relate in terms of succinctness.
Good-for-games automata are known to be exponentially more succinct than
deterministic automata, but the gap between good-for-MDPs and good-for-games
automata as well as the gap between ordinary nondeterministic automata and
those that are good-for-MDPs have been open. We establish that these gaps are
exponential, and sharpen this result by showing that the latter gap remains
exponential when restricting the nondeterministic automata to separating safety
or unambiguous reachability automata.Comment: 18 page