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    Morphology (CS 626-449) : by Mugdha Bapat Under The Guidance of Prof. Pushpak Bhattacharyya

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    Tanmay Purandare
    This document discusses morphology, which is the study of words and how they are formed. It covers topics like the internal structure of words, word formation rules, and how morphology is used in natural language processing and information retrieval. It also discusses concepts like morphemes, inflection, derivation, morphological parsing, and resources needed for morphological analysis like lexicons and orthographic rules.

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    Morphology (CS 626-449) : by Mugdha Bapat Under The Guidance of Prof. Pushpak Bhattacharyya

    Uploaded by

    Tanmay Purandare
    31 views23 pages
    This document discusses morphology, which is the study of words and how they are formed. It covers topics like the internal structure of words, word formation rules, and how morphology is used in natural language processing and information retrieval. It also discusses concepts like morphemes, inflection, derivation, morphological parsing, and resources needed for morphological analysis like lexicons and orthographic rules.

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    This document discusses morphology, which is the study of words and how they are formed. It covers topics like the internal structure of words, word formation rules, and how morphology is used in natural language processing and information retrieval. It also discusses concepts like morphemes, inflection, derivation, morphological parsing, and resources needed for morphological analysis like lexicons and orthographic rules.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
    Download as pdf or txt
    31 views23 pages

    Morphology (CS 626-449) : by Mugdha Bapat Under The Guidance of Prof. Pushpak Bhattacharyya

    Uploaded by

    Tanmay Purandare
    This document discusses morphology, which is the study of words and how they are formed. It covers topics like the internal structure of words, word formation rules, and how morphology is used in natural language processing and information retrieval. It also discusses concepts like morphemes, inflection, derivation, morphological parsing, and resources needed for morphological analysis like lexicons and orthographic rules.

    Copyright:

    © All Rights Reserved
    Download as PDF, TXT or read online from Scribd
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    of 23

    Morphology (CS 626-449)

    By Mugdha Bapat
    Under the guidance of
    Prof. Pushpak Bhattacharyya
    What is Morphology?
    • Study of Words
    – Their internal structure
    washing wash -ing

    – How they are formed?


    bat bats rat rats
    write writer browse browser

    • Morphology tries to formulate rules


    Morphology for NLP
    • Machine Translation

    पुःतक, Noun, Direct Case, Plural


    Analyze Generate
    Transfer

    िकताब: िकताब, Noun, पुःतके


    Direct Case, Plural

    • Information Retrieval
    – goose and geese are two words referring to the same
    root goose
    Need of MA and MG
    • Why not list all the forms of a word along with
    their features?
    – Drink:
    – drink, V, 1st person
    – drink, V, 2nd person
    – drink, V, 3rd person, plural
    – Drinks: drink, V, 3rd person, singular
    – Drank: …
    – Drunk: …
    – Drinking: …
    Need of MA and MG
    • Reasons:
    – Productivity: going, drinking, running, playing
    • Storing every form leads to inefficiency
    – Addition of new words
    • Verb: To fax. Forms: fax, faxes, faxed, faxing
    – Morphological complex languages: Marathi
    • दारासमोरयांनी – दार(SG)+समोर+चा(PL)+नी
    Meaning: दरवाजेके सामनेवाल ने
    • Polymorphemic
    • Possible to store all the forms?
    Morphemes
    • Smallest meaning bearing units constituting a
    word
    Stem
    Morphemes Prefix Suffix
    consider
    re ation

    Stem Affixes
    reconsideration

    tree, go, fat Prefixes Suffixes

    Affixes in
    post -
    (postpone)
    -ed (tossed) Hindi?
    Classes of Morphology

    • Inflection
    • Derivation
    Inflection
    • Indicates some grammatical function like
    Case लड़का (D) लड़के(O)
    Number लड़का (Sg) लड़के(Pl)
    Person जाऊँगा (1st) जाओगे(2nd)
    Gender जाऊँगा(Masc) जाऊँगी (Fem)
    Tense गया(Pas) जाऊँगी (Fem)

    • Results in a word of the same class


    • Productivity
    Derivation
    • Usually, results in a word of a different class
    • -able when attached to a verb gives an adjective
    • read (V) + -able = readable (Adj)
    • Often meaning of the derived word is difficult to
    predict exactly
    • writer :: writer (one who writes)
    • paint :: painter (one who paints)
    • cut :: cutter? (an instrument used to cut)
    • Less productive
    – eatable :: readable :: runnable?
    Problems in MA
    • Productivity
    • False Analysis
    • Bound Base Morphemes
    Productivity
    • Property of a morphological process to give rise to new
    formations on a systematic basis
    Transitive Verb Productive
    -able
    (read) (readable)

    Not
    Noun (game) -able Productive
    (gameable)

    • Exceptions
    Peaceable Actionable Companionable

    Saleable Marriageable Reasonable

    Impressionable Fashionable knowledgeable


    False analysis

    hospitable, sizeable

    They don’t have the meaning “to be able”


    They can not take the suffix -ity to form a noun

    Analyzing them as the words containing suffix


    -able leads to false analysis
    Bound Base Morphemes
    • Occur only in a particular complex word
    • Do not have independent existence

    base morpheme
    Compound
    (nonexistent) (known)

    malleable • -able has the regular meaning


    “be able”
    • -ity form is possible
    feasible • Base words don’t exit
    (fease+ible) independently
    More on Inflection
    Noun inflectional suffixes •Plural marker -s
    •Possessive marker ‘s

    Verb inflectional suffixes •Third person present singular


    marker
    -s
    •Past tense marker -ed
    •Progressive marker -ing
    •Past participle markers -en or –ed

    Adjective inflectional suffixes •Comparative marker -er


    •Superlative marker -est

    Inflectional Suffixes in English


    Spelling Rules
    • Generally words are pluralized by adding –s to
    the end
    • Words ending in –s, -z, -sh and sometimes –x
    require –es
    – buses, quizzes, dishes, boxes
    • Nouns ending in –y preceded by a consonant
    change the –y to -i
    – babies, floppies
    Verbal Inflection
    Morphological Regularly Inflected Verbs Irregularly Inflected Verbs
    Form Classes
    Stem Jump Parse Fry Sob Eat Bring Cut

    -s form Jumps Parses Fries Sobs Eats Brings Cuts

    -ing participle Jumping Parsing Frying Sobbing Eating Bringing Cutting

    Past form Jumped Parsed Fried Sobbed Ate Brought Cut

    –ed participle Jumped Parsed Fried Sobbed Eaten Brought Cut

    Forms governed by spelling rules


    Idiosyncratic forms
    Morphological Parsing
    • Finding
    – Constituent morphemes
    – Features
    Input Morphological Parsed Output
    cats cat +N +PL
    geese goose +N +PL
    goose (goose +N +SG) or (goose +V)
    gooses goose +V +3G
    caught (catch +V +PAST-PART) or (catch +V +PAST)
    Resources
    Lexicon List of stems and suffixes along
    with basic information about
    them
    Morphotactics A model of morpheme ordering
    that explains which classes of
    morphemes can follow other
    classes of morphemes
    Orthographic Rules Spelling rules used to model
    the changes that occur in the
    work usually when two
    morphemes combine
    Morphological Recognition
    reg-noun irregular-sg-noun irregular-pl-noun plural

    Lexicon flower goose geese -s


    cat sheep sheep
    dog mouse mice
    Morphological Recognition: Nouns
    reg-noun irregular-sg-noun irregular-pl-noun plural

    Lexicon flower goose geese -s


    cat sheep sheep
    dog mouse mice

    reg-noun plural (-s)

    q0 q1 q2
    FSA Note: Here, we are
    ignoring the nouns
    irreg-pl-noun which take the suffix
    –es for pluralization

    irreg-sg-noun
    Adjectives
    Type Properties Examples

    adj-root1 Occur with un- and -ly happy, real


    Adj-root2 Can’t occur with un- and big, red
    -ly
    Adjectives
    Type Properties Examples
    adj-root1 Occur with un- and -ly happy, real
    Adj-root2 Can’t occur with un- and big, red
    -ly

    adj-root1
    -er
    -ly
    un- q1 q2 -est

    q0 adj-root1 q5

    ε
    q3 q4 -er
    -est

    adj-root2
    References
    • “Linguistics, An Introduction to Language and
    Communication” by Adrian Akmajian, Richard A.
    Demers, Ann K. Farmer and Robert M. Harnish (5th
    Edition)
    • SPEECH and LANGUAGE PROCESSING, An
    Introduction to Natural Language Processing,
    Computational Linguistics, and Speech Recognition
    by Daniel Jurafsky and James H. Martin (Second
    Edition)

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