tailieunhanh - Báo cáo khoa học: "PARSING A FREE-WORD ORDER LANGUAGE: WARLPIRI"

Free-word order languages have long posed significant problems for s t a n d a r d parsing algorithms. This paper reports on an implemented parser, based on GovernmentBinding theory (GB) (Chomsky, 1981, 1982), for a particular free-word order language, Warlpiri, an aboriginal language of central Australia. The parser is explicitly designed to transparently mirror the principles of GB. The operation of this parsing system is quite different in character from that of a rule-based parsing system, ~., a context-free parsing method. In this system, phrases are constructed via principles of selection, case-marking, caseassignment, and argument-linking, rather than by. | PARSING A FREE-WORD ORDER LANGUAGE WARLPIRI Michael B. Kashket Artificial Intelligence Laboratory Massachusetts Institute of Technology 545 Technology Square room 823 Cambridge MA 02139 ABSTRACT Free-word order languages have long posed significant problems for standard parsing algorithms. This paper reports on an implemented parser based on Government-Binding theory GB Chomsky 1981 1982 for a particular free-word order language Warlpiri an aboriginal language of central Australia. The parser is explicitly designed to transparently mirror the principles of GB. The operation of this parsing system is quite different in character from that of a rule-based parsing system . a context-free parsing method. In this system phrases are constructed via principles of selection case-marking caseassignment and argument-linking rather than by phrasal rules. The output of the parser for a sample Warlpiri sentence of four words in length is given. The parser was executed on each of the 23 other permutations of the sentence and it output equivalent parses thereby demonstrating its ability to correctly handle the highly scrambled sentences found in Warlpiri. INTRODUCTION Basing a parser on Government-Binding theory has led to a design that is quite different from traditional The parser presented here operates in two stages lexical and syntactic. Each stage is carried out by the same parsing engine. The lexical parser projects each constituent lexical item morpheme according to information in its associated lexical entries. Lexical parsing is highly data-driven from entries in the lexicon in keeping with GB. Lexical parses returned by the first stage are then handed over to the second stage the syntactic parser as input where they are further projected and combined to form the final phrase marker. Before plunging into the parser itself a sample Warl-piri sentence is presented. Following this the theory of argument . NP identification is given in order to show how