• Journal of KIISE:Software and Applications
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• v.37 no.6
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• pp.446-454
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• 2010

According to the original chart parsing algorithm, a sentence is parsed in a strict left-to-right order. The modified chart parsing algorithm proposed in this paper breaks the strictness. With the proposed algorithm, a sentence is parsed in a random order. Conventional left-to-right parsing is also possible, since left-to-right parsing is a special case of random-order parsing. The proposed parsing algorithm is an extension of chart parsing algorithm and its control structure is very simple, so that it is easy to implement the algorithm.

• Journal of KIISE:Software and Applications
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• v.36 no.7
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• pp.571-579
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• 2009

A left-comer and look-ahead chart parsing algorithm suppresses the generation of meaningless intermediate structures, and thus, gains parsing speed-ups. However, the algorithm requires additional costs to maintain left-comer and look-ahead information throughout the parsing process. Albeit the additional costs, previous research shows that significant parsing speed-ups have been achieved for large-sized context-free grammars. In this paper, we perform similar experiments with a small-sized grammar. We still get parsing speed-ups, but relatively low. We also find that left-comer information has rather negative effects on parsing speed-ups.

• Korean Journal of Cognitive Science
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• v.4 no.1
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• pp.177-212
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• 1993

My research is based on the parser for ill-formed input by Mellish in a paper in ACL 27th meeting Proceedings. 1989. My system is composed of two parsers:WFCP and IFCP. When WFCP fails to give the parse tree for the input sentence, the sentence is identified as ill-formed and is parsed by IFCP for error detection and recovery at the syntactic level. My system is indendent of grammatical rules. It does not take into account semantic ill-formedness. My system uses a grammar composed of 25 context-free rules. My system consistes of two major parsing strategies:top-down expection and bottem-up satisfaction. With top-down expectation. rules are retrieved under the inference condition and expaned by inactive arcs. When doing bottom-up parsing. my parser used two modes:Left-Right parsing and Right-to-Left parsing. My system repairs errors sucessfully when the input contains an omitted word or an unknown word substitued for a valid word. Left- corner and right-corner errors are more easily detected and repaired than ill-formed senteces where the error is in teh middle. The deviance note. with repair details, is kept in new inactive arcs which are generated by the error correction procedure. The implementation of my system is quite different from Mellish's. When rules are invoked. my system invokes all rules with minimal inference. My bottom up parsing strategy uses Left-to-Right mode and Right-to-Left mode. My system is bottom-up-parsing-oriented like the chart parser. Errors are repaired in two ways:using top-down hypothesis, and using Need-Chart which keeps the information of expectation and complection of expanded goals by rules. To reduce the number of top-down cycles. all rules are invoked simultaneously and this invocation information is kept in Need-Chart. This idea will be extended for the implementation of multiple error recovery system.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.5
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• pp.127-137
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• 1996

In this paper, an algorithm for on-line rightward japanese parsing is proposed. The ambiguity in on-line parsing is accumulated until the input is completely finished, since there is not a space between words in the japanese sentence. Thus the algorithm for morphological analysis, based on modified chart, is used in solving it. And the number of searching a word in dirctionary for morphological analysis is also a puzzling problem. The japanese sentence, consist of N characters, has logically its maximum number of N(N+1)/2 searches in the ordinary on-line analysis, which is nearly twice as many as normal off-line. In this paper, the matter is settled through the modification of dictionary format. In experiment, we can accomplish the rate of analysis which is nearly equal to that of off-line parsing. And it becomes clear that the longer a sentence is, the better an analysis efficiency is.

• Annual Conference on Human and Language Technology
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• 1993.10a
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• pp.15-24
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• 1993

한국어는 구문요소의 문법기능이 표면구조상에 명시되는 구문특성을 갖고 있다. 이러한 특성은 한국어의 문법체계가 feature중심으로 전개되고 있음을 의미한다. 한국어에서의 feature 특성과 이진 결합 관계를 중심으로 하는 chart parsing 알고리즘을 제시하고 한국어 chart parser을 구현하였다.

• Journal of KIISE:Software and Applications
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• v.28 no.5
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• pp.448-448
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• 2001

The definitions in Korean dictionary not only describe meanings of title, but also include various semantic information such as hypernymy/hyponymy, meronymy/holonymy, polysemy, homonymy, synonymy, antonymy, and semantic features. This paper purposes to implement a parser as the basic tool to acquire automatically the semantic information from the definitions in Korean dictionary. For this purpose, first we constructed the part-of-speech tagged corpus and the tree tagged corpus from the definitions in Korean dictionary. And then we automatically extracted from the corpora the frequency of words which are ambiguous in part-of-speech tag and the grammar rules and their probability based on the statistical method. The parser is a kind of the probabilistic chart parser that uses the extracted data. The frequency of words which are ambiguous in part-of-speech tag and the grammar rules and their probability resolve the noun phrase's structural ambiguity during parsing. The parser uses a grammar factoring, Best-First search, and Viterbi search In order to reduce the number of nodes during parsing and to increase the performance. We experiment with grammar rule's probability, left-to-right parsing, and left-first search. By the experiments, when the parser uses grammar rule's probability and left-first search simultaneously, the result of parsing is most accurate and the recall is 51.74% and the precision is 87.47% on raw corpus.

• KIPS Transactions on Software and Data Engineering
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• v.5 no.1
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• pp.21-28
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• 2016

The performance of an English-Korean machine translation system depends heavily on its English parser. The parser in this paper is a part of the rule-based English-Korean MT system, which includes many syntactic rules and performs the chart-based parsing. The parser generates too many structures due to many syntactic rules, so much time and memory are required. The rule-based parser has difficulty in analyzing and translating the long sentences including the commas because they cause high parsing complexity. In this paper, we propose the 3-phase parsing method with sentence segmentation to efficiently translate the long sentences appearing in usual. Each phase of the syntactic analysis applies its own independent syntactic rules in order to reduce parsing complexity. For the purpose, we classify the syntactic rules into 3 classes and design the 3-phase parsing algorithm. Especially, the syntactic rules in the 3rd class are for the sentence structures composed with commas. We present the automatic rule acquisition method for 3rd class rules from the syntactic analysis of the corpus, with which we aim to continuously improve the coverage of the parsing. The experimental results shows that the proposed 3-phase parsing method is superior to the prior parsing method using only intra-sentence segmentation in terms of the parsing speed/memory efficiency with keeping the translation quality.

• Proceedings of the Korean Information Science Society Conference
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• 2003.04c
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• pp.507-509
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• 2003

본 논문에서 제안하는 영어 Parser는 Bottom-Up Best-First Chart Parser를 기반으로 영어 구문 분석과 동시에 영$\longrightarrow$한 구조변환을 수행한다. 따라서, 영어 입력문에 대한 파서의 결과는 한국어 구운 Tree가 된다. 구문 분석과 변환을 동시에 수행하므로, 번역 과정을 단순화하고 번역지식 관리가 용이하여 번역기의 튜닝이 용이하다. 구현된 파서는 대규모 문법 규칙에 대응하기가 용이하고. 새로운 규칙의 추가가 용이하여 번역기의 점진적인 성능 향상이 가능하다.

• Annual Conference on Human and Language Technology
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• 1989.10a
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• pp.15-20
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• 1989

이 논문은 상대적으로 어순이 자유로운 언어인 한국어의 특성을 반영하면서, 모든 가능한 문장 구조를 분석할 수 있는 한국어 분석 방법을 제시한다. 특히 구절 구조에 의한 통사 표현 기능을 하위 범주화와 단일화에 의해 보완하는 기법을 이용하면서, bottom-up과 left-right에 의해 분석이 가능한 단일 과정 (one-path) 분석 기법을 이용하는 것이 본 논문의 특징이다. 그리고 하위 범주화와 서술어의 어미가 가진 양상 정보에 의존하여 한국어의 내포문 처리가 이루어져야함을 보여준다.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.4
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• pp.183-190
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• 1996

The purpose of this paper is to show that the solutions of the problem for the anaphor ocured in korean senstence, by means of one-direction activated chart parsing leaded by a head. This is the phenomenon frequently occured in the conversation of natural language and the part necessarily required in the construction of natural language processing system for the practical use. To solve the problem of anaphor in the korean language, we have computerized definition and the management conditions necessary in the semantic classification between the anaphor and its antecedent and index are added in the feature structure in lexicon. To deal with anaphor in parser and algorithm is proposed to solve the problem for anaphor. The range of management of pareser is extended to solve the problem for anaphor of the indeclinable parts of speech in korean occured in all the sentences the parser HPSG developed previously manages.