Vladimír Kadlec

New meta-grammar constructs in czech language parser synt

In this paper, we present and summarize the latest development of the Czech sentence parsing system synt. The presented system uses the meta-grammar formalism, which enables to define the grammar with a maintainable number of meta-rules. At the same time, these meta-rules are translated into rules for efficient and fast head driven chart parsing supplemented with evaluation of additional contextual constraints. The paper includes a comprehensive description of the meta-grammar constructs as well as actual running times of the system tested on corpus data.

Dependency and phrasal parsers of the Czech language: a comparison

In the paper, we present the results of an experiment with comparing the effectiveness of real text parsers of Czech language based on completely different approaches - stochastic parsers that provide dependency trees as their outputs and a meta-grammar parser that generates a resulting chart structure representing a packed forest of phrasal derivation trees. We describe and formulate main questions and problems accompanying such experiment, try to offer answers to these questions and finally display also factual results of the tests measured on 10 thousand Czech sentences.

New Methods for Pruning and Ordering of Syntax Parsing Trees

Most robust rule-based syntax parsing techniques face the problem of high number of possible syntax trees as the output. There are two possible solutions to this: either release the request for robustness and provide special rules for uncovered phenomena, or equip the parser with filtering and ordering techniques. We describe the implementation and evaluation of the latter approach. In this paper, we present new techniques of pruning and ordering the resulting syntax trees in the Czech parser synt. We describe the principles of the methods and present results of measurements of effectiveness of these methods both per method and in combination, as computed for 10,000 corpus sentences.

Grammatical Heads Optimized for Parsing and Their Comparison with Linguistic Intuition

This paper deals with head-driven chart parsing on large natural-language grammars. We present a procedure that optimizes positions of heads in the grammar rules based on the number of edges in the resulting chat. New performance evaluation tool PACE is briefly introduced first. The head-optimizing procedure is described and the results are given. The last part compares the head positions obtained automatically with those set according to traditional linguistics.