Context-sensitive grammar

About: Context-sensitive grammar is a research topic. Over the lifetime, 1938 publications have been published within this topic receiving 45911 citations. The topic is also known as: CSG.

Some Preservation Properties of Normal Form Grammars

Abstract: The normal form grammars, such as those developed by Chomsky and Greibach, preserve certain properties of the original grammar. Ordinarily attention is only directed to weak equivalence, that is, that the original grammar and its normal form version both generate the same language. By paying greater attention to the functions carrying a grammar to its normal form, considerably stronger preservation properties can be proved. We demonstrate that several normal forms preserve ambiguities. More surprisingly, a variant of Chomsky’s normal form, called canonical two form, forms an adjunction in connection with the original grammar. This fact shows that canonical two form preserves a large number of the structural properties of the original grammar. In particular, we show that the canonical two form is $LR(k)$ if the original grammar is $LR(k)$, strengthening a result of Gray and Harrison. Preservation of structural properties such as ambiguity is important in semantic considerations, and the methods given for t...

Inference of edge replacement graph grammars

Abstract: We describe an algorithm and experiments for inference of edge replacement graph grammars. This method generates candidate recursive graph grammar productions based on isomorphic subgraphs which overlap by two nodes. If there is no edge between the two overlapping nodes, the method generates a recursive graph grammar production with a virtual edge. We guide the search for the graph grammar based on the size of the grammar and the portion of the graph described by the grammar. We show experiments where we generate graphs from known graph grammars, use our method to infer the grammar from the generated graphs, and then measure the error between the original and inferred grammars. Experiments show that the method performs well on several types of grammars, and specifically that error decreases with increased numbers of unique labels in the graph.

Attribute grammars in the functional style

Abstract: For a long time, attribute grammars have formed an isolated programming formalism. We show how we may embed the attribute grammar approach in a modern functional programming language. The advantages of both sides reinforce each other: the former provides compositionality and the latter naming abstraction and higher-orderness. Through a sequence of program transformations we show different aspects of the techniques involved. We conclude with the observation that an attribute grammar oriented algorithm development may be a fruitful one, and may go hand in hand with a more algebraic style of program development.

On TAG and Multicomponent TAG Parsing

Abstract: The notion of mild context-sensitivity is an attempt to express the formal power needed to define the syntax of natural languages. However, all incarnati- ons of mildly context-sensitive formalisms are not equivalent. On the one hand, near the bottom of the hierarchy, we find tree adjoining grammars and, on the other hand, near the top of the hierarchy, we find multicomponent tree adjoining grammars. This paper proposes a polynomial parse time method for these two tree rewriting formalisms. This method uses range concatenation grammars as a high-level intermediate definition formalism, and yields several algorithms. Range concatenation grammar is a syntactic formalism which is both powerful, in so far as it extends linear context-free rewriting systems, and efficient, in so far as its sentences can be parsed in polynomial time. We show that any unrestricted tree adjoining grammar can be transformed into an equivalent range concatenation grammar which can be parsed in O(n6) time, and, moreover, if the input tree adjoining grammar has some restricted form, its parse time decreases to O(n5). We generalize one of these algorithms in order to process multicomponent tree adjoining grammars. We show some upper bounds on their parse times, and we introduce a hierarchy of restricted forms which can be parsed more efficiently. Our approach aims at giving both a new insight into the multicomponent adjunction mechanism and at providing a practical implementation scheme.

Mild context-sensitivity and tuple-based generalizations of context-free grammar

Abstract: This paper classifies a family of grammar formalisms that extend context-free grammar by talking about tuples of terminal strings, rather than independently combining single terminal words into larger single phrases. These include a number of well-known formalisms, such as head grammar and linear context-free rewriting systems, but also a new formalism, (simple) literal movement grammar, which strictly extends the previously known formalisms, while preserving polynomial time recognizability. The descriptive capacity of simple literal movement grammars is illustrated both formally through a weak generative capacity argument and in a more practical sense by the description of conjunctive cross-serial relative clauses in Dutch. After sketching a complexity result and drawing a number of conclusions from the illustrations, it is then suggested that the notion of mild context-sensitivity currently in use, that depends on the rather loosely defined concept of constant growth, needs a modification to apply sensibly to the illustrated facts; an attempt at such a revision is proposed.