Iterative CKY Parsing for Probabilistic Context-Free Grammars
نویسندگان
چکیده
This paper presents an iterative CKY parsing algorithm for probabilistic contextfree grammars (PCFG). This algorithm enables us to prune unnecessary edges produced during parsing, which results in more efficient parsing. Since pruning is done by using the edge’s inside Viterbi probability and the upper-bound of the outside Viterbi probability, this algorithm guarantees to output the exact Viterbi parse, unlike beam-search or bestfirst strategies. Experimental results using the Penn Treebank II corpus show that the iterative CKY achieved more than 60% reduction of edges compared with the conventional CKY algorithm and the run-time overhead is very small. Our algorithm is general enough to incorporate a more sophisticated estimation function, which should lead to more efficient parsing.
منابع مشابه
K-best Iterative Viterbi Parsing
This paper presents an efficient and optimal parsing algorithm for probabilistic context-free grammars (PCFGs). To achieve faster parsing, our proposal employs a pruning technique to reduce unnecessary edges in the search space. The key is to repetitively conduct Viterbi inside and outside parsing, while gradually expanding the search space to efficiently compute heuristic bounds used for pruni...
متن کاملParsing Strategies for the Integration of Two Stochastic Context-free Grammars
Integration of two stochastic context-free grammars can be useful in two pass approaches used, for example, in speech recognition and understanding. Based on an algorithm proposed by [Nederhof and Satta, 2002] for the non-probabilistic case, left-to-right strategies for the search for the best solution based on CKY and Earley parsers are discussed. The restriction that one of the two grammars m...
متن کاملTowards efficient probabilistic HPSG parsing: integrating semantic and syntactic preference to guide the parsing
We present a framework for efficient parsing with probabilistic Head-driven Phrase Structure Grammars (HPSG). The parser can integrate semantic and syntactic preference into figures-of-merit (FOMs) with the equivalence class function during parsing, and reduce the search space by using the integrated FOMs. This paper presents a CKY algorithm with this function and experimental results of beam t...
متن کاملA CKY parser for picture grammars
We study the complexity of the membership or parsing problem for pictures generated by a family of picture grammars: Siromoney’s Context-Free Kolam Array grammars (coincident with Matz’s context-free picture grammars). We describe a new parsing algorithm, which extends the Cocke, Kasami and Younger’s classical parsing technique for string languages and preserves the polynomial time complexity.
متن کاملAccelerating the CKY Parsing Using FPGAs
The main contribution of this paper is to present an FPGA-based implementation of an instance-specific hardware which accelerates the CKY (Cocke-Kasami-Younger) parsing for context-free grammars. Given a context-free grammar G and a string x, the CKY parsing determines whether G derives x. We have developed a hardware generator that creates a Verilog HDL source to perform the CKY parsing for an...
متن کامل