Linguistic Essentials

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Linguistic Essentials

• 2002. 2. 15.
• ???

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Introduction

• Contents
• Parts of Speech and Morphology
• Parts of Speech
• Morphological process
• Nouns and pronouns
• Determiners and adjectives
• Verbs
• Other parts-of-speech
• Phrase Structure
• Introduction
• Phrase structure grammars
• Dependency Arguments and adjuncts
• X theory
• Phrase structure ambiguity
• Semantics and Pragmatics

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Part of Speech and MorphologyPart of Speech (1/2)

• Parts of Speech
• a group of words which show similar syntactic
  behavior, and often a typical semantic type.
• three important POS noun, verb, adjective
• Noun typically refer to people, animals,
  concepts and things.
• Verb express the action in a sentence.
• Adjective describe a property of noun.
• many words have multiple POS.
• POS tag
• more fine-grained classifications of word classes
  than traditional systems.
• well-established sets of abbreviations for word
  class names.
• Brown Corpus is used in this chapter.
• Ex adjectives JJ

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Part of Speech and MorphologyPart of Speech (1/2)

• POS separate Lexical / Functional categories
• Lexical categories ( open categories )
• Have a large number of members.
• New words are commonly added.
• Ex nouns, verbs, adjectives
• Functional categories ( closed categories )
• Have only a few members
• Normally have a clear grammatical use.
• Ex prepositions, determiners

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Part of Speech and MorphologyMorphological
process (1/2)

• Morphological process
• Word categories are systematically related by
  morphological process
• Major types of morphological process
• inflection, derivation, compounding
• Inflection
• systematic modifications of a root form by means
  of prefixes and suffixes
• Not change word class or meaning significantly.
• Varies features such as tense, number, plurality.
• lexeme a group of the inflectional forms of a
  word.
• Example
• dog ? dogs, speech ? speeches
• change ? changed, change ? changing

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Part of Speech and MorphologyMorphological
process (2/2)

• Derivation
• more radical change of syntactic category and
  often involves a change in meaning.
• less systematic than inflection
• Example
• adjective ? adverb ( -ly ) wide-ly
• adjective ? verb ( -en ) weak-en, soft-en
• verb ? adjective ( -able ) accept-able
• verb ? noun ( -er ) teach-er, lead-er
• Compounding
• the merging of two or more words into a new word.
• pronounced as a single word denote a single
  semantic concept
• Ex tea kettle, disk drive, downmarket, mad cow
  disease

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Part of Speech and MorphologyNouns and Pronouns
(1/3)

• Nouns
• typically refer to entities in the world like
  people, animals, and things.
• Common Inflections of nouns
• number singular, plural
• In English
• usually regular pattern ( suffix s ), and other
  is irregular
• gender feminine(female), masculine(male),
  neuter(neither)
• English does not have a system of gender
  inflections.
• Example of Latin -a for feminine and us for
  masculine.
• case nominative, genitive, dative, accusative
• different forms when they have different
  functions ( subject, object, etc. )
• Example of Latin
• the Latin for son filius ( subject ) and
  filium ( object of a verb ).

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Part of Speech and MorphologyNouns and Pronouns
(2/3)

• Pronouns
• a separate small class of words that acts like
  variables in that they refer to a preson or thing
  that is somehow salient in the discourse context.
• In English
• nominative(subject case) ? accusative(object
  case)
• different forms when they are used as the subject
  and the object of a sentence.
• posessive pronouns
• when pronouns are a possessor
• ex my car
• reflexive pronous ( anaphors )
• always refer to a nearby antecedent in the same
  sentence.
• normally the subject of the sentence.
• ex Mary saw herself in the mirror. ? Mary saw
  her in the mirror.

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Part of Speech and MorphologyNouns and Pronouns
(3/3)

• Brown tags
• two special types of nouns in Brown tag set.
• proper nouns
• refer to particular persons or things. ( ex
  Mary, United States )
• adverbial nouns
• without modifiers to give information about the
  circumstances of the event described. ( ex
  home, west, tomorrow )

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Part of Speech and MorphologyDeterminers and
adjectives (1/3)

• Determiners
• describe the particular reference of a noun.
• subtype
• articles the, a, an
• demonstratives this, that
• Adjectives
• describe properties of nouns.
• Used such as attributive(adnominal), or
  predicative.
• attributive a red rose, this long journey.
• predicative The rose id red., The journey will
  be long.
• In English, the form of adjectives
• positive the basic form of the adjective. (
  rich, trendy, intelligent )
• morphological modifications
• the derivational endings like ly
• the comparative form ( richer, trendier )
• the superlative form ( richest, trendiest )
• periphstic form ( more intelligent, most
  intelligent )

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Part of Speech and MorphologyDeterminers and
adjectives (2/3)

• Brown tags
• adjective
• positive form JJ, comparative JJR,
  superlatives JJT
• semantically superlative adjectives ( chief,
  main, top ) JJS
• numbers ( subclasses of adjectives )
• cardinals ( one, two ) CD
• ordinals ( first, second ) OD
• determiners
• articles AT
• singular determiners ( this, that ) DT
• plural determiners ( these, those ) DTS
• determiners that can be singular or plural (
  some, any ) DTI
• double conjunction determiners ( either,
  neither ) DTX

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Part of Speech and MorphologyDeterminers and
adjectives (3/3)

• Quantifiers
• express ideas like all, many, some.
• pre-quantifier ( all, many ) ABN
• nominal quantifier ( one, something, somebody )
  PN
• there ( when used to express existence at the
  beginning of a sentence ) EX
• the interrogative pronous and determiners which
  are used for questions and relative clauses
• nominative wh-pronoun ( who, which, that ) WPS
• objective wh-pronoun ( which, that ) WPO
• possessive wh-pronoun ( whose ) SP
• wh-determiner ( what, which ) WDT

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Part of Speech and MorphologyVerbs (1/2)

• Verbs
• used to describe actions, activities and states.
• morphological forms
• base form
• present tense ( Ex I walk., You walk., She
  walks )
• infinitive with to ( Ex She likes to walk., To
  walk is fun. )
• bare infinitive ( Ex She shouldnt walk. )
• -ing form
• progressive ( Ex She is walking., She will be
  walking. )
• gerund ( Ex Walking is fun. )
• -ed form
• past tense ( Ex She walked. )
• present perfect ( Ex She has walked. )
• past perfect ( Ex She had walked. )
• many verbs are irregular
• drive ? She drove the car. she has never driven a
  car.
• take ? She took off on Monday. She had already
  taken off on Monday.

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Part of Speech and MorphologyVerbs (2/2)

• Grammatical Feature
• Morphologically ( Ex -s, -ing, -ed. )
• Means of auxiliaries ( Ex have, be, will )
• Auxiliaries
• Express aspect, mood, and some tense information.
• Periphrastic forms built using auxiliaries
• The modal auxiliaries ( modals )
• Express modalities like possibility ( may, can )
  or obligation ( should )
• Ex He may or may not come to the meeting.
• Ex You should spend more time with your family.
• Brown tags
• Base form VB
• The third person singular VBZ
• The past tense VBD
• Gerund and present participle VBG
• The past participle VBN
• Modal auxiliaries ( can, may, must, ) MD

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Part of Speech and MorphologyOther parts of
speech (1/3)

• Adverbs, prepositions, and particles
• Adverb
• adverbs modify a verb. ( specify place, time,
  manner, or degree )
• Ex She often travels to Las Vegas.
• some adverbs modify adjectives and other adverb
• Ex A very unlikely event., a shockingly frank
  exchange.
• degree adverb
• modify adjectives, adverbs and do not modify
  verbs.
• sometimes regarded as a separate POS called
  qualifiers.
• Ex very
• Brown tags
• ordinary adverb ( simply, late, well, little )
  RB
• comparative adverb ( later, better, less ) RBR
• superlative adverb ( latest, best, least ) RBT
• qualifier ( very, too, extremely ) QL
• post-qualifier ( enough, indeed ) QLP
• adverbial and interrogative functions
• wh-qualifier ( how ) WQL
• wh-adverb ( how, when, where ) WRB

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Part of Speech and MorphologyOther parts of
speech (2/3)

• Prepositions and particles
• preposition
• express spatial relationships.
• Ex in the glass, on the table, over their
  heads.
• particles
• a subclass of prepositions that can enter into
  strong bonds with verbs in the formations of
  so-called phrasal verbs.
• phrasal verbs a separate lexical entry with
  syntactic and semantic properties different from
  the verb it was formed from.
• Ex The plane took off at 8am. Dont give in to
  him. He put me off.
• Brown tags
• prepositions IN
• particles RP

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Part of Speech and MorphologyOther parts of
speech (3/3)

• Conjunctions and complementizers
• Coordinating conjunctions
• joins two sentences as equals.
• Ex husband and wife
• Ex She bought or leased the car.
• Subordinating conjunctions
• attach a secondary sentence to a primary
  sentence.
• secondary sentence often expresses a proposition,
  a reason, a condition, a concession or a
  temporally related event.
• Ex She said that he would be late.
• Ex I wont wait if he is late.
• Complementizers
• a conjunction which marks a complement clause ( a
  notional sentence or predication that is an
  argument of a predicate ).
• Ex I know that he is here
• Brown tags
• conjunctions CC
• subordinating conjunctions CS

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Phrase StructureIntroduction (1/3)

• Syntax
• the study of the regularities and constraints of
  word order and phrase structure.
• Paradigmatic relationship
• groupings of words behave as constituents.
• example of positioning and phrasal expansion for
  a constituent
• I put the bagels in the freezer. The bagels, I
  put in the freezer.
• 
  saw
  .
• Syntagmatic relationship
• form a phrase like sewed clothes or sewed a
  dress.
• collocations is important class of
  syntagmatically related words.

the tall woman the tall woman with sad eyes
the very short man the short man with red hair
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Phrase StructureIntroduction (2/3)

• Major phrase types
• Noun phrase ( NP )
• noun is the head of the noun phrase.
• uses
• the arguments of verbs
• the participants in the action
• activity or state described by the verb
• constituent
• optional determiner
• zero or more adjective phrases
• a noun head
• some post-modifiers (ex prepositional phrases
  or clausal modifiers)
• relative clauses clausal modifiers of nouns.
• Example The homeless old man in the park that I
  tried to help yesterday.
• Prepositional phrases ( PPs )
• headed by a preposition and contain a noun phrase
  complement.
• usually express spatial and temporal locations
  and other attributes.

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Phrase StructureIntroduction (3/3)

• Verb phrase ( VP )
• the verb is the head of the verb phrase.
• the verb phrase organizes all elements of the
  sentence that depend syntactically on the verb.
• the verb phrase does not contain the subject noun
  phrase.
• Example
• Getting to school on time was a struggle.
• He was trying to keep his temper.
• That woman quickly showed me the way to hide.
• Adjective phrases ( APs )
• complex adjective phrase are less common.
• Example
• She is very sure of herself.
• He seemed a man who was quite certain to succeed.

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Phrase StructurePhrase structure grammars (1/3)

• syntactic analysis of a sentence
• how to determine the meaning of the sentence from
  the meaning of the words.
• word order allows us to infer who did what to
  whom.
• Example Mary gave Peter a book. Peter gave
  Mary a book.
• English word order
• Subject Verb Object declaratives
• the subject and first auxiliary verb are inverted
  interrogatives.
• no subject imperatives
• free word order language
• use case marking to indicate who did what to
  whom.
• word order isnt used to indicate who the doer
  is.
• word order is then usually used mainly to
  indicate discourse structure.

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Phrase StructurePhrase structure grammars (2/3)

• Rewrite Rules
• Form category ? category
• ex S ? NP VP
• the symbol on the left side can be rewritten as
  the sequence of symbols on the right side.
• possibilities for rewriting depend solely on the
  category, and not on any surrounding context. (
  context-free grammars )
• derivation example
• recursivity
• rewrite rules can be applied an arbitrary number
  of times.

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Phrase StructurePhrase structure grammars (3/3)

• Phrase structure grammars Feature
• non-local dependencies
• subject-verb agreement
• subject and verb agree even if other words and
  phrases intervene.
• Ex The women who found the wallet were given a
  reward.
• long-distance dependencies
• example wh-extraction
• Should Peter buy a book? ? Which book should
  Peter buy?
• There is a long-distance dependency between buy
  and which book.
• empty node
• occur when a non-terminal may be rewritten as
  nothing.
• Example
• imperatives ( Ex Eat the cake! )
• no subject NP, so adding a rule NP ? ?

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Phrase StructureArguments and adjuncts(1/4)

• Dependents
• example Sue watched the man at the next table.
• Sue and the man are dependents of a watching
  event
• Sue and the man are the two arguments of the verb
  watch.
• Classification of the arguments
• semantic roles
• agent the person or thing that is doing
  something.
• patient the person or thing that is having
  something done to it.
• Ex Children eat sweet candy.
• The children is the agent of the action of
  eating. ( sweet candy patient )
• grammatical relations
• subject the noun phrase that appears before the
  verb.
• object noun phrase, which normally appears
  immediately after the verb.
• Ex Children eat sweet candy.
• The children is the subject of eat. ( sweet candy
  object )
• systematic associations semantic roles and
  grammatical functions.
• active voice agent subject, patient object.
• passive voice patient subject, agent
  oblique role.

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Phrase StructureArguments and adjuncts(2/4)

• Classify the dependents of verbs.
• Arguments
• express entities that are centrally involved in
  the activity of the verb.
• most argument expressed as NPs may be PPs, VPs,
  or as clauses
• example
• We deprived him of food.
• John knows that he is losing.
• She put the book on the table.
• He will retire in Florida.
• Adjuncts
• phrases that have a less tight link to the verb.
• describe the time, place, or manner of that the
  verb describes.
• example
• She saw a Woody Allen movie yesterday.
• She saw a Woody Allen movie with great interest.
• He gave his presentation on the stage.
• I straightened the nail with a hammer.

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Phrase StructureArguments and adjuncts(3/4)

• Subcategorization
• the classifications of verbs according to the
  types of complements they permit.
• list of subcategorized arguments
• Subject The children eat candy.
• Object The children eat candy.
• Prepositional phrase She put the book on the
  table.
• Predicative adjective We made the man angry.
• Bare infinitive She helped me walk.
• Infinitive with to She likes to walk.
• Participial phrase She stopped singing that
  tune eventually.
• That-clause She thinks that it will rain
  tomorrow.
• Question-form clauses She is wondering why it
  is raining in August.

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Phrase StructureArguments and adjuncts(4/4)

• subcategorization frame ( syntactic regularity )
• a particular set of arguments that a verb can
  appear with.
• Intransitive verb NPsubject.
• ex The woman walked.
• Transitive verb NPsubject, NPobject.
• ex John loves Mary.
• Ditransitive verb NPsubject, NPdirect
  object, NPindirect object.
• ex Mary gave Peter flowers.
• Intransitive with PP NPsubject, PP.
• ex I rent in Paddington.
• Transitive with PP NPsubject, NPobject, PP.
• ex She put the book on the table.
• Sentential complement NPsubject, clause.
• ex I know (that) she likes you.
• Transitive with sentential complement
  NPsubject, NPobject, clause.
• ex She told me that Gary is coming on Tuesday.
• selectional restrictions ( semantic regularity )
• Ex The dog barked all night. ? The cat barked
  all night.
• Ex I eat vegetables every day ? I eat
  philosophy every day.

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Phrase StructureX theory

• X Theory
• importance of a word will be the head of a
  phrase.
• noun and preposition are the head of a noun and
  preposition phrase respectively. and others are
  dependent to head word.
• name X is taken to represent a variable across
  lexical categories.
• Three level in X Theory
• The head is always the first (X) level
• the phrase is the XP level
• X is an intermediate level
• General pattern of constituency is repeated
  across phrase types in final step.

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Phrase StructurePhrase structure ambiguity (1/2)

• Parsing
• the process of reconstructing the derivation(s)
  or phrase structure tree(s) that give rise to a
  particular sequence of words.
• parse a phrase structure tree that is
  constructed from a sentence.
• Phrase structure ambiguity ( syntactic ambiguity
  )
• there are many different phrase structure trees
  that could all have given rise to a particular
  sequence of words.
• attachment ambiguity
• phrases generated by two different nodes.
• Ex The children ate the cake with a spoon.

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Phrase StructurePhrase structure ambiguity (2/2)

• garden pathing
• the phenomenon of first being tricked into
  adopting a spurious parse and then having to
  backtrack to try to construct the right parse.
• Ex The horse raced past the barn fell.
• The horse raced past the barn fell cannot
  be added to parse.
• backtrack to raced and construct a complete
  different parse tree, that meaning is The horse
  fell after it had been raced past the barn.
• Ungrammatical
• ungrammatical sentence has no parse tree.
• sentence does not have an interpretation at all.
• Ex Slept children the.
• semantic abnormality
• sentence that semantic interpretation is
  incoherent.
• Ex Colorless green ideas sleep furiously. The
  cat barked.

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Semantics and Pragmatics (1/2)

• Semantics
• the study of the meaning of words, constructions,
  and utterances.
• Divide two part
• meaning of individual words ( lexical semantics )
• one approach how word meanings are related to
  each other.
• hypernymy more general sense.
• hyponymy more specialized meaning.
• antonyms opposite meanings.
• meronymy part-whole relationship.
• holonym whole corresponding to a part.
• synonyms same meaning
• homonyms written same way, but really different
  meanings.
• polyseme a words meaning are related.
• meaning of sentences
• how meanings of individual words are combined.
• natural language does not obey compositionality (
  predicted from the meaning of the parts. )
• collocations
• sum of the meaning of the part additional
  meaning
• Ex white wine, white skin.

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Semantics and Pragmatics (2/2)

• Pragmatics
• the study of how knowledge about the world and
  language conventions interact with literal
  meaning.
• Discourse analysis
• explain the covert relationships between
  sentences in a text.
• central problem anaphoric relations
• Ex Mary helped Peter get out of the cab. He
  thanked her.
• Peter and He refer to the same person.
• important for information extraction.
• areas of pragmatics
• most areas have not received much attention in
  Statistical NLP.
• hard to model the complexity of world knowledge
  with statistical means.
• lack of training data.
• two areas are beginning to receive more attention
• the resolution of anaphoric relations
• the modeling of speech acts in dialogues.