Tractability issues in extraposition grammar
نویسندگان
چکیده
Extraposition Grammar (XG) was introduced in Per81] as a grammar formalism whose increase in recognizing power over context free grammars is limited to mechanisms for adequate description of structural phenomena occurring in natural language. This paper proposes versions of XG whose xed recognition problems are in deterministic polynomial and exponential time; furthermore it is shown that the unrestricted XG deened in the original work Per81] describe any recursively enumerable language. Research (NWO). The paper is a preliminary version of material to appear in a larger document on various applications of simple literal movement grammar (LMG).
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Extraposition Grammars
This paper presents a grammar formalism for natural language analysis, called extraposition grammars (XGs), based on the subset of predicate calculus known as definite, or Horn, clauses. It is argued that certain important linguistic phenomena, collectively known in t ransformational grammar as left extraposition, can be described better in XGs than in earlier grammar formalisms based on defini...
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