Milena Hnátková

The Linguistic Basis of a Rule-Based Tagger of Czech

This paper describes the conception of a rule-based tagger (part-of-speech disambiguator) of Czech currently developed for tagging the Czech National Corpus (cf. [2]). The input ofthe tagger consists ofsentences whose words are assigned all possible morphological analyses. The tagger disambiguates this input by successive elimination oftags which are syntactically implausible in the sentential context ofthe particular word. Due to this, the tagger promises substantially higher accuracy than current stochastic taggers for Czech. This is documented by the results concerning the disambiguation ofthe most frequent ambiguous word form in Czech-the word se.

Morphological Disambiguation of Multiword Expressions and Its Impact on the Disambiguation of Their Environment in a Sentence

Abstract This study concerns the impact of the collocation/phraseme disambiguation component within the complex system of the rule-based morphological disambiguation of Czech. This system constitutes one of the two main disambiguation subsystems that are responsible for the morphological disambiguation of the corpora of synchronic Czech within the Czech National Corpus project. We will show that although the part of texts constituted by collocations/phrasemes (generally multiword expressions – MWEs) is relatively small and consequently the errorfree morphological disambiguation of MWEs covers only a small portion of textual material, such perfectly disambiguated fragments in sentences help to improve the disambiguation of the rest, non-MWE part of sentences.

Eye of a Needle in a Haystack

We propose a multidimensional taxonomy of multiword expressions (MWEs) as a pattern applicable to entries in a representative lexicon of Czech MWEs. The taxonomy and the lexicon are useful for many reasons concerning lexicography, teaching Czech as a foreign language, and theoretical issues of MWEs as entities standing between lexicon and grammar, as well as for NLP tasks such as tagging and parsing, identification and search of MWEs, or word sense and semantic disambiguation. In addition to the description of various types of idiomaticity, the taxonomy and the lexicon are designed to account for flexibility in morphology and word order, syntactic and lexical variants and even creatively used fragments.

INFERENCING ON LINGUISTICALLY BASED SEMANTIC STRUCTURES

The paper characterizes natural language inferencing in the TIBAQ method of question-answering, focussing on three aspects: (i) specification of the structures on which the inference rules operate, (ii) Classification of the rules that have been formulated and implemented up to now, according to the kind of modification of the input structure the rules invoke, and (iii) discussion of some points in which a properly designed inference procedure may help the search of the answer, and vice versa.