We present a hierarchical chunk-to-string translation model, which can be seen as a compromise between the hierarchical phrasebased model and the tree-to-string model, to combine the merits of the two models. With the help of shallow parsing, our model learns rules consisting of words and chunks and meanwhile introduce syntax cohesion. Under the weighed synchronous context-free grammar defined ...

Context-awareness refers to the ability to sense and adapt to context. With the rise of context-aware systems, designers are struggling with what variables should be sensed from the context. According to the definitions found in the literature, whether something belongs to context, has to do with whether it is relevant. However, what it means to be relevant is left implicit in these definitions...

The growing importance of context-awareness in the construction of adaptable systems requires the development of formal models and notations that can bring this new dimension from middleware concerns into the higher levels of modelling. In this paper, we propose a formal approach to the design of context-aware systems that is well integrated with the concepts and techniques that have been propo...

In this paper, we introduce the notions of context-sensitive and TOL collage grammars as generalizations of context-free collage grammars. Both kinds of picture generating devices are more powerful than the context-free case. Nevertheless, the sizes of collages in a TOL collage language can be shown to grow at most exponentially. In contrast to this, there are no such bounds for context-sensiti...

Seki et al. (1991) proved a rather weak pumping lemma for multiple context-free languages, which says that any infinite m-multiple context-free language contains a string that is pumpable at some 2m substrings. We prove a pumping lemma of the usual universal form for the subclass consisting of well-nested multiple context-free languages. This is the same class of languages generated by non-dupl...

The application of Genetic Programming (GP) to the discovery of empirical laws most often suffers from two limitations. The first one is the size of the search space; the second one is the growth of non-coding segments, the introns, which exhausts the memory resources as GP evolution proceeds. These limitations are addressed by combining Genetic Programming and Stochastic Grammars. On one hand,...

Context-sensitive grammars in which each rule is of the forln aZfl-~ (-*Tfl are acyclic if the associated context-free grammar with the rules Z ~ 3' is acyclic. The problem whether an intmt string is in the language generated by an acyclic context-sensitive grammar is NP-conlplete.

We present a novel method for the computation of prefix probabilities for linear context-free rewriting systems. Our approach streamlines previous procedures to compute prefix probabilities for context-free grammars, synchronous context-free grammars and tree adjoining grammars. In addition, the methodology is general enough to be used for a wider range of problems involving, for example, sever...

Over the last decade, probabilistic parsing has become the standard in the parsing literature where one of the purposes of those probabilities is to discard unlikely parses. We investigate the effect that discarding low probability parses has on both the weak and strong generative power of context-free grammars. We prove that probabilistic context-free grammars are more powerful than their non-...

We propose a new graphical model, called Sequential Interval Network (SIN), for parsing complex structured activity whose composition can be represented as a string-length limited stochastic context-free grammar. By exploiting the grammar, the generated network captures the activity’s global temporal structure while avoiding time-sliced manner model. In this network, the hidden variables are th...