Probabilistic regular graphs

Deterministic graph grammars generate regular graphs, that form a structural extension of configuration graphs of pushdown systems. In this paper, we study a probabilistic extension of regular graphs obtained by labelling the terminal arcs of the graph grammars by probabilities. Stochastic properties of these graphs are expressed using PCTL, a probabilistic extension of computation tree logic. We present here an algorithm to perform approximate verification of PCTL formulae. Moreover, we prove that the exact model-checking problem for PCTL on probabilistic regular graphs is undecidable, unless restricting to qualitative properties. Our results generalise those of EKM06, on probabilistic pushdown automata, using similar methods combined with graph grammars techniques.Comment: In Proceedings INFINITY 2010, arXiv:1010.611

A uniform architecture for parsing and generation

The use of a single grammar for both parsing and generation is an idea with a certain elegance, the desirability of which several researchers have noted. In this paper, we discuss a more radical possibility: not only can a single grammar be used by different processes engaged in various "directions" of processing, but one and the same language-processing architecture can be used for processing the grammar in the various modes. In particular, parsing and generation can be viewed as two processes engaged in by a single parameterized theorem prover for the logical interpretation of the formalism. We discuss our current implementation of such an architecture, which is parameterized in such a way that it can be used for either purpose with grammars written in the PATR formalism. Furthermore, the architecture allows fine tuning to reflect different processing strategies, including parsing models intended to mimic psycholinguistic phenomena. This tuning allows the parsing system to operate within the same realm of efficiency as previous architectures for parsing alone, but with much greater flexibility for engaging in other processing regimes.Engineering and Applied Science

XMG : eXtending MetaGrammars to MCTAG

In this paper, we introduce an extension of the XMG system (eXtensibleMeta-Grammar) in order to allow for the description of Multi-Component Tree Adjoining Grammars. In particular, we introduce the XMG formalism and its implementation, and show how the latter makes it possible to extend the system relatively easily to different target formalisms, thus opening the way towards multi-formalism.Dans cet article, nous présentons une extension du système XMG (eXtensible MetaGrammar) afin de permettre la description de grammaires darbres adjoints à composantes multiples. Nous présentons en particulier le formalisme XMG et son implantation et montrons comment celle-ci permet relativement aisément détendre le système à différents formalismes grammaticaux cibles, ouvrant ainsi la voie au multi-formalisme

Complexity of normal form grammars

AbstractVarious types of grammars can be used to describe context-free languages. Such are context-free grammars and their normal form restrictions. Rewriting of a context-free grammar to an equivalent grammar in required (normal) form can cause a change of parameters of the grammar such as the number of rules, the number of nonterminals, etc. Greibach normal form grammars and position restricted grammars will be investigated from the point of view of descriptional complexity of context-free languages