Linguistic Essentials 1 Parts of Speech and Morphology

Linguistic Essentials 1

Parts of Speech and Morphology 4 Parts of Speech correspond to syntactic or grammatical categories such as noun, verb, adjectives and prepositions. 4 Word categories are systematically related by morphological processes such as the formation of plural form from the singular form. 2

Parts of Speech 4 Nouns, verbs, adjectives 4 Determiners 4 Adverbs She ran very quickly; She often travels to Vegas; She started off impressively. 4 Preposition She looked up the tree 4 Particles She looked up the number 4 Conjunctions, complementizer She is afraid that …. Funny but stupid 3

Syntax or Phrase Structure: A simple context-free grammar 4 S --> NP VP 4 NP --> AT NNS | 4 AT --> the 4 NNS --> children | AT NN | NP PP 4 VP --> VP PP | VBD NP 4 P --> IN NP students | mountains 4 VBD --> slept | ate | saw 4 IN --> in | of 4 NN --> cake The Grammar The Lexicon 4

Syntax or Phrase Structure: A Parse Tree S NP VP AT NNS VBD The children ate NP AT NN the cake 5

Local and Non-Local Dependencies 4 A local dependency is a dependency between two words expressed within the same syntactic rule. 4 A non-local dependency is an instance in which two words can be syntactically dependent even though they occur far apart in a sentence (e. g. , subject-verb agreement; long-distance dependencies such as wh-extraction). 4 Non-local phenomena are a challenge for certain statistical NLP approaches (e. g. , n-grams) that model local dependencies. 6

Semantic Roles 4 Most commonly, noun phrases are arguments of verbs. These arguments have semantic roles: the agent of an action, the patient and other roles such as the instrument or the goal. 7

Subcategorization 4 Different verbs can relate different numbers of entities: transitive versus intransitive verbs. 4 Verbs are classified according to the type of complements they permit. This called subcategorization. 4 Frame. Net combines semantic roles and subcategorization. Let’s look up “put. v” 8

Attachment Ambiguity and Garden-Path Sentences 4 Attachment ambiguities occur with phrases that could have been generated by two different nodes in the parse tree. E. g. : The children ate the cake with a spoon. 4 Garden-Path sentences are sentences that lead you along a path that suddenly turns out not to work. E. g. : The horse raced past the barn fell. 9

Semantics 4 Semantics is the study of the meaning of words, constructions, and utterances. 4 Semantics can be divided into two parts: lexical semantics and combination semantics. 4 Lexical semantics: hypernymy, hyponymy, antonymy, meronymy, holonymy, synonymy, homonymy, polysemy, and homophony (no need to memorize!). 4 Compositionality: the meaning of the whole is built up from the meanings of its parts; language is often not compositional, though. 4 Idioms correspond to cases where the compound phrase means something completely different from its parts. 10

Pragmatics 4 Pragmatics is the area of studies that goes beyond the study of the meaning of a sentence and tries to explain what the speaker really is expressing. 4 Understand the scope of quantifiers, speech acts, discourse analysis, anaphoric relations. 11