Eva Hajičová

The Prague Dependency Treebank

The availability of annotated data (with as rich and “deep” annotation as possible) is desirable in any new developments. Textual data are being used for so-called training phase of various empirical methods solving various problems in the field of computational linguistics. While there are many methods that use texts in their plain (or raw) form (in most cases for so-called unsupervised training), more accurate results may be obtained if annotated corpora are available. The data annotation itself is a complex task. While morphologically annotated corpora (pioneered by Henry Kucera in the 60’s) are now available for English and other languages, syntactically annotated corpora are rare. Inspired by the Penn Treebank, the most widely used syntactically annotated corpus of English, we decided to develop a similarly sized corpus of Czech with a rich annotation scheme.

On the role of the hierarchy of activation in the process of natural language understanding

The elements of the stock of knowledge shared by the speaker and the hearer change their salience, in the sense of being immediately accessible in the hearers memory. The hierarchy of salience is argued to be a basic component of a mechanism serving for the identification of reference. Some of the regularities of this mechanism are discussed, the description of which is a necessary prerequisite of an automatic understanding of connected texts.

The ordering principle

Abstract The objective of the present paper is to point out the existence of a principle governing the ordering of a sentences major constituents (Section 1). This principle is closely related to the pragmatically based (though linguistically structured) topic-focus articulation of the (meaning of a) sentence, and therefore we also mention the operational tests used to analyze this articulation and characterize the semantic relevance of topic and focus, and of the communicative dynamism (CD) (section 2). We show how these phenomena can be economically described on the basis of Chomskys theta theory, if the ordering principle is treated by the categorial component (Section 3).

A Functional Approach to Syntax in Generative Description of Language

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The Current Status of the Prague Dependency Treebank

The Prague Dependency Treebank (PDT) project is conceived of as a many-layered scenario, both from the point of view of the stratal annotation scheme, from the division-of-labor point of view, and with regard to the level of detail captured at the highest, tectogrammatical layer. The following aspects of the present status of the PDT are discussed in detail: the now-available PDT version 1.0, annotated manually at the morphemic and analytic layers, including the recent experience with post-annotation checking; the ongoing effort of tectogrammatical layer annotation, with a specific attention to the so-called model collection; and to two different areas of exploitation of the PDT, for linguistic research purposes and for information retrieval application purposes.

Identifying topic and focus by an automatic procedure

An algorithm for automatic identification of topic and focus of the sentence is presented, based on dependency syntax and using written input, which is much more ambiguous than spoken utterance.

Tagging of very large corpora: topic-focus articulation

After a brief characterization of the theory of the topic-focus articulation of the sentence (TFA), rules are formulated that determine the assignment of appropriate values of the TFA attribute in the process of syntactico-semantic tagging of a very large corpus of Czech.

Hierarchy of salience and discourse analysis and production

The hierarchy of salience of the items of the knowledge assumed by the speaker to be shared by him and by the hearer constitutes one aspect of a dynamic account of discourse (Sect. 1). It is claimed that a representation of this hierarchy is a good support for discourse analysis (reference assignement, Sect. 2) and for discourse production (pronominalization, definite description, Sect. 3).

ON THE ROLE OF LINGUISTIC SEMANTICS

We want to present some support for the suggestion that a counterpart of Carnaps intensional structure may be specified, for natural language, as the semantic representations of sentences, if belief (and other intensional) contexts are kept apart from metalinguistic assertions. Semantic representations should include the topic/focus articulation and other empirically based issues that can be checked linguistically, while the interplay of meaning postulates and a translation procedure should account for the relationship between semantic representations and propositions. It is also suggested that the relationship between concepts and objects ist not fully symmetrical to that between propositions and truth values.

Stock of shared knowledge: a tool for solving pronominal anaphora

The paper develops further the idea of using the notion of the stock of shared knowledge (SSK) for anaphora resolution following a more subtle treatment of the influence of the topic/focus articulation of the sentence on the degrees of salience of items of the SSK. An algorithmic evaluation procedure of the SSK is formulated taking into account the notions of contextual boundness, syntactic associations, complexity of the sentences and existence/nonexistence of possible competitors, and a general evaluating function is proposed, essential for the process of anaphora resolution. In the present paper the analysis is performed for Czech; however, the considerations are claimed to be of a universal validity, the actual relations between different factors and the values, of course, being language-dependent.