Guido Minnen

Applied morphological processing of English

We describe two newly developed computational tools for morphological processing: a program for analysis of English inflectional morphology, and a morphological generator, automatically derived from the analyser. The tools are fast, being based on finite-state techniques, have wide coverage, incorporating data from various corpora and machine readable dictionaries, and are robust, in that they are able to deal effectively with unknown words. The tools are freely available. We evaluate the accuracy and speed of both tools and discuss a number of practical applications in which they have been put to use.

Robust, applied morphological generation

In practical natural language generation systems it is often advantageous to have a separate component that deals purely with morphological processing. We present such a component: a fast and robust morphological generator for English based on finite-state techniques that generates a word form given a specification of the lemma, part-of-speech, and the type of inflection required. We describe how this morphological generator is used in a prototype system for automatic simplification of English newspaper text, and discuss practical morphological and orthographic issues we have encountered in generation of unrestricted text within this application.

Memory-based learning for article generation

Article choice can pose difficult problems in applications such as machine translation and automated summarization. In this paper, we investigate the use of corpus data to collect statistical generalizations about article use in English in order to be able to generate articles automatically to supplement a symbolic generator. We use data from the Penn Treebank as input to a memory-based learner (TiMBL 3.0; Daelemans et al., 2000) which predicts whether to generate an article with respect to an English base noun phrase. We discuss competitive results obtained using a variety of lexical, syntactic and semantic features that play an important role in automated article generation.

Magic for Filter Optimization in Dynamic Bottom-Up Processing

Off-line compilation of logic grammars using Magic allows an incorporation of filtering into the logic underlying the grammar. The explicit definite clause characterization of filtering resulting from Magic compilation allows processor independent and logically clean optimizations of dynamic bottom-up processing with respect to goal-directedness. Two filter optimizations based on the program transformation technique of Unfolding are discussed which are of practical and theoretical interest.

Direct automated inversion of logic grammars

Reversibility of logic grammars in natural language processing is desirable for both theoretical and practical reasons. This paper addresses this topic in describing a new approach to automated inversion of logic grammars: the Direct Inversion Approach (dia). A logic grammar is inverted by automatically altering the order of literals in the grammar and reformulating certain recursive procedures at compile time. The inversion process results in a new executable grammar, which is evaluated top-down and left-to-right (using a standard Prolog interpreter), but not left-to-right with respect to the original grammar. Thedia improves upon related approaches not only in being fully automated and computationally tractable, but also with respect to the class of grammars it is able to invert and the performance of the new executable grammar produced.

Off-line optimization for Earley-style HPSG processing

A novel approach to HPSG based natural language processing is described that uses an off-line compiler to automatically prime a declarative grammar for generation or parsing, and inputs the primed grammar to an advanced Earley-style processor. This way we provide an elegant solution to the problems with empty heads and efficient bidirectional processing which is illustrated for the special case of HPSG generation. Extensive testing with a large HPSG grammar revealed some important constraints on the form of the grammar.

Selective magic HPSG parsing

We propose a parser for constraint-logic grammars implementing HPSG that combines the advantages of dynamic bottom-up and advanced top-down control. The parser allows the user to apply magic compilation to specific constraints in a grammar which as a result can be processed dynamically in a bottom-up and goal-directed fashion. State of the art top-down processing techniques are used to deal with the remaining constraints. We discuss various aspects concerning the implementation of the parser as part of a grammar development system.

PREDICTIVE LEFT-TO-RIGHT PARSING OF A RESTRICTED VARIANT OF TAG(LD/LP)

By means of a factorization of linear precedence (LP) information in tree‐adjoining grammar (TAG), the possibility to capture syntactic generalizations can be enhanced, especially with respect to languages which exhibit relative free word‐order. In TAG(LD/LP) LP‐information is factorized in a way reminiscent of the ID/LP format of CFGs. However, in contrast to its context‐free counterpart, in TAG(LD/LP) entanglement of constituents is allowed by admitting not only the permutation of sister nodes, but also of non‐sister nodes in a structural description. In this paper a generalization of the predictive left‐to‐right parser for TAG is presented which is able to handle a restricted variant of TAG(LD/LP), which allows the permutation of sister nodes and non‐sister nodes within elementary structures, the basic building blocks of TAG(LD/LP).