We develop a language model using probabilistic context-free grammars (PCFGs) that is “pseudo context-sensitive” in that the probability that a nonterminal N expands using a rule T depends on N’s parent. We give the equations for estimating the necessary probabilities using a variant of the inside-outside algorithm. We give experimental results showing that, beginning with a high-performance PC...

We present conditions under which graph transformation rules can be applied in time independent of the size of the input graph: graphs must contain a unique root label, nodes in the left-hand sides of rules must be reachable from the root, and nodes must have a bounded outdegree. We establish a constant upper bound for the time needed to construct all graphs resulting from an application of a f...

This paper presents an approach to truth and the Liar paradox which combines elements of context dependence and hierarchy. This approach is developed formally, using the techniques of model theory in admissible sets. Special attention is paid to showing how starting with some ideas about context drawn from linguistics and philosophy of language, we can see the Liar sentence to be context depend...

Parsing for mildly context-sensitive language formalisms is an important area within natural language processing. While the complexity of the parsing problem for some such formalisms is known to be polynomial, this is not the case for all of them. This article presents a series of results regarding the complexity of parsing for linear context-free rewriting systems and deterministic tree-walkin...

We present an approach for learning context-dependent semantic parsers to identify and interpret time expressions. We use a Combinatory Categorial Grammar to construct compositional meaning representations, while considering contextual cues, such as the document creation time and the tense of the governing verb, to compute the final time values. Experiments on benchmark datasets show that our a...

In this work we establish that the language MIX = {w ∈ {a; b; c}||w|a = |w|b = |w|c} and the language O2 = {w ∈ {a; a; b; b}||w|a = |w|a ∧ |w|b = |w|b} are 2-MCFLs. As 2-MCFLs form a class of languages that is included in both the IO and OI hierarchies, and as O2 is the group language of a simple presentation of Z we exhibit here the first, to our knowledge, non-virtually-free group language (i...

Matrix grammars introduced by Nbrah~tm (1965) have proved to be a very fruitful generalization of context-free grammars: simple in principle, easy to deal with and yet very powerful [cf. Brainerd (1968), Ibarra (1970) and Siromoney (1969)]. They fall into the category of grammars with restricted use of productions, and possess the same generative capacity as programmed grammars, periodically ti...

The development of Web applications based on Service Oriented Architectures (SOA) is challenged by the lack of support to the specification of explicit context adaptation policies. As an answer to this issue, we present the Context Aware Workflow Execution framework (CAWE), which enriches SOA with (a) context-aware workflow management; (b) dialog management capabilities supporting the adaptatio...

The pumping lemma and Ogden lemma offer a powerful method to prove that a particular language is not context-free. In 2008 Kanazawa proved an analogue of pumping lemma for well-nested multiplecontext free languages. However, the statement of lemma is too weak for practical usage. We prove a stronger variant of pumping lemma and an analogue of Ogden lemma for the class of tree-adjoining language...