Basic categorial grammars are enriched with a conjunction operation, and it is proved that the formalism obtained in this way has the same expressive power as conjunctive grammars, that is, context-free grammars enhanced with conjunction. It is also shown that categorial grammars with conjunction can be naturally embedded into the Lambek calculus with conjunction and disjunction operations. Thi...

The definition of combinatory categorial grammar (CCG) in the literature varies quite a bit from author to author. However, the differences between the definitions are important in terms of the language classes of each CCG. We prove that a wide range of CCGs are strongly context-free, including the CCG of CCGbank and of the parser of Clark and Curran (2007). In light of these new results, we tr...

In this paper, we demonstrate that probabilistic context free grammars (PCFGs) can be used to recognize events from a sensor data stream. A fast PCFG inference algorithm based on Stolcke(1994) and Chen(1996) is presented which utilizes the set of observation strings as training data. A realworld scenario is presented and we also show that multi-modal sensor information can be utilized using Dem...

We investigate Global Index Grammars (GIGs), a grammar formalism that uses a stack of indices associated with productions and has restricted context-sensitive power. We discuss some of the structural descriptions that GIGs can generate compared with those generated by LIGs. We show also how GIGs can represent structural descriptions corresponding to HPSGs (Pollard and Sag, 1994) schemas.

This paper reports on the implementation of the Latvian grammar checker. It gives a brief introduction of the project scope – Latvian language, the previous implementation of the grammar checker and its limitations. Then, it describes the proposed approach. This paper also describes the Latvian parser used for this project and the quality measurement methods used for the quality assessment of t...

It is often assumed that ‘grounded’ learning tasks are beyond the scope of grammatical inference techniques. In this paper, we show that the grounded task of learning a semantic parser from ambiguous training data as discussed in Kim and Mooney (2010) can be reduced to a Probabilistic Context-Free Grammar learning task in a way that gives state of the art results. We further show that additiona...

We present an approach specifying constraints on labeled trees, such as are commonly used within (computational) linguistic theories, and show how to translate these constraints to formal grammars, in particular context-free grammars and (lexicalized) tree adjoining grammars. Our method offers the formal advantages of constraint-based formalisms and at the same time operational efficiency for t...

A context-free grammar and its derivations can be described by a Petri net, called a context-free Petri net, whose places and transitions correspond to the nonterminals and the production rules of the grammar, respectively, and tokens are separate instances of the nonterminals in a sentential form. Therefore, the control of the derivations in a context-free grammar can be implemented by adding ...

We show that the free weakly E-ample monoid on a set X is a full submonoid of the free inverse monoid FIM(X) on X . Consequently, it is ample, and so coincides with both the free weakly ample and the free ample monoid FAM(X) on X . We introduce the notion of a semidirect product Y ∗ T of a monoid T acting doubly on a semilattice Y with identity. We argue that the free monoid X∗ acts doubly on t...

We apply basic notions of the theory of rough sets, due to Pawlak [30, 31], to explicate certain properties of unification-based learning algorithms for categorial grammars, introduced in [6, 11] and further developed in e.g. [18, 19, 24, 25, 26, 9, 28, 14, 15, 3]. The outcomes of these algorithms can be used to compute both the lower and the upper approximation of the searched language with re...