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本文是一篇英语语法论文，本文将目标词may划分为三个基本语义：root possibility,epistemic possibility和permission；can划分为三个基本语义：ability,root possibility和permission。基于形式概念分析理论，以从500万字自建多体裁语料库中提取的300个例句为对象，以在目标词出现的语境中提取的特征为属性，建立形式背景，并采用过滤法与属性偏序图相结合的方法对该数据集进行语义分类规则提取，分别得出了英语情态动词can和may的语义分类规则，can的语义分类正确率达到了95.00%，may的分类正确率达到了98.33%。

Chapter 1 Introduction

1.1 Research background

English modal verbs are used to express speakers’attitude toward the truth of aproposition.However,the senses of English modal verbs are complicated and ambiguous,which causes difficulty in language comprehension.As Palmer(1990:1)once mentioned:“modal verb might be the most complex but important item in the English grammarsystem”.Although English modal verbs have been studied by many scholars,the wordsense ambiguity of English modal verbs is still a tough issue.In the studies of word senseclassification,many features are extracted and some of them are redundant features.Therefore,the study of feature selection for sense classification is of great importance inlinguistic studies.

With the help of computer science,sense classification has been conducted in naturallanguage processing.Some scholars have made fruitful achievements in senseclassification of nouns,notional verbs,modal verbs and prepositions.Yu(2011)generatesthe WSD models of must by using the method of BP neutral network and support vectormachine.Li(2016)adopts attribute partial ordered structure diagram to study the featureselection of preposition on for WSD.

FCA(formal concept analysis)is a mathematical theory put forward by Wille(1982).It is widely used in knowledge discovery of big data and natural language processing.Attribute partial ordered structure diagram(APOSD)is a mathematical method developedfrom FCA theory,and is frequently used in knowledge discovery.On the basis of FCA andAPOSD,some researches have been conducted.Yu,Hong and Li(2013)investigates theword sense disambiguation and knowledge discovery of English modal verbs by formal concept analysis.

1.2 Research objectives and significance

There are three objectives of this research.Firstly,this research aims at finding outthe optimal features that are effective to the sense classification of English modal verb canand may,respectively.Secondly,this study will investigate the simple class exclusivefeatures and the composite class exclusive features for sense classification of Englishmodal verb can and may.Lastly,the relations between the word senses and the selectedfeatures will be investigated.

The significance of the research is mainly on the following aspects.Theoretically,this study will provide a new method for investigating deep semantic structure of Englishmodal verbs.Practically,this study can provide a reference for the later researches onnatural language processing(NLP),such as text classification and machine translation.Besides,this study can extends the range of application of feature selection,especially inlinguistic field.

Chapter 2 Literature Review

2.1 Studies on English modality

Aristotle,a Greek philosopher,is the first one who put forward the concept ofmodality,which can be dated back to two thousand years ago.The notions of possibility,necessity and the relationship among them are the research focuses of Aristotle.Sincemodal is greatly r本论文由英语论文网提供整理，提供论文代写，英语论文代写，代写论文，代写英语论文，代写留学生论文，代写英文论文，留学生论文代写相关核心关键词搜索。