Presentation on theme: "Projecting Grammatical Features in Nominals: Cognitive Theory and Computational Model October 2009 Jerry Ball Air Force Research Laboratory."— Presentation transcript:
Projecting Grammatical Features in Nominals: Cognitive Theory and Computational Model October 2009 Jerry Ball Air Force Research Laboratory
2 Theoretical Alignment Cognitive Linguistics – No autonomous syntax – Grammatical categories are semantically motivated Construction Grammar – Constructions at multiple levels of idiomaticity – No sharp distinction between lexicon and syntax X-Bar Theory – Prior to introduction of functional heads – Functional categories—head, specifier, modifier, complement—explicitly represented
3 Theoretical Alignment Simpler Syntax, Conceptual Semantics; GPSG HPSG SBCG; TGG G & B/P & P Minimalism; TAG; LFG; Role & Reference Grammar; Functional Grammar; OT…Descriptive Grammars…DRT; CCG Cross Language & Diachronic research Competing Linguistic Theories can inform and constrain each other – No one theory has all the right answers – We need all the constraints we can get
4 Theoretical Alignment Computational Linguistic Research can inform and constrain linguistic theory – Human language is (at least) mildly context sensitive (Joshi et al., 1991) – Human language processing appears to be nearly deterministic (Marcus, 1980) Processing doesn’t slow down with length of input – Large coverage systems need probabilistic mechanisms to handle rampant ambiguity Performance considerations can inform and constrain linguistic Competence – “Grammars are ‘frozen’ or ‘fixed’ performance preferences” (Hawkins, 2004)
5 Theoretical Alignment Psycholinguistic Research can inform and constrain linguistic theory – Human language processing is incremental (word by word) (Bever, 1970; Tanenhaus et al., 1995) Garden path sentences – “The horse raced past the barn fell” Visual World Paradigm – Human language processing is interactive (Tanenhaus et al. 1995) Visual World Paradigm “the green…” “put the arrow on the paper into the box”
6 Representational Commitments Localist theory of the representation and projection of grammatical features in nominals – No access to non-local features Specifiers & Modifiers (aka Adjuncts), in addition to Heads, project grammatical features At level of nominal (NP), projected features are collected into a set without duplicates Redundantly encoded features may occasionally conflict – without the expression being ungrammatical Grammatical features may be unspecified – without the expression being ungrammatical
7 Grammatical Features (in English) Definiteness – Universal, Definite, Indefinite, Negative (Zero) Number – Singular, Plural, Mass (Singular) Animacy – Animate, Inanimate, Human (Animate) Gender – Male, Female, Neuter Person – First, Second, Third Case – Subjective, Objective, Genitive Wh, Distance (Near, Far), Measure (Comparative, Superlative)
8 Representational Commitments Selective encoding of grammatical features – Where there is no grammatical distinction, there is no grammatical feature Without grammatical evidence, there is no basis for learners of English to learn the distinction Important to distinguish grammatical function (head, specifier, modifier, complement) from part of speech (noun, verb) or phrasal form (NP, VP) – Head of a nominal need not be a noun! – Modifier may be adjective, numeral, noun or verb participle!
9 Processing Commitments Incremental (word by word), serial, pseudo- deterministic processing mechanism which builds representation, operating over… Interactive (context-sensitive), parallel, probabilistic, constraint-based mechanism which selects from competing alternatives (but does not build structure) At each choice point, interactive mechanism selects best alternative based on current local context Incremental mechanism uses selection to build linguistic representation
10 Processing Commitments Non-monotonic mechanism of context accommodation for handling conflicts – Modest adjustment of representation – Part and parcel of normal processing – not reanalysis! – Feature overriding Replace previous value with new value – Feature blocking Block new value from projecting Construal mechanism for handling unspecified features – Referent of expression may provide (semantic) basis for construal
11 Computational Implementation Implemented in ACT-R Cognitive Architecture (Anderson, 2007) – Theory of human cognition based on 30+ years of research – Computational implementation – Hundreds of small-scale models implemented in ACT-R – Few large-scale models…
12 Representational Considerations Four primary grammatical functions in nominals (adapted from X-Bar Theory before functional heads): – Specifier Deteminers typically function as specifiers – “the man” – “those men” Quantifiers often function as specifiers – “some men” Possessive nominals/pronouns function as specifiers – “the man’s book” – “my book” Important to distinguish grammatical function from POS or phrasal form!
13 Representational Considerations – Head Nouns typically function as heads – “the man” Verb participles occasionally function as heads – “the running of the bulls” Verbs function as heads in expressions like – “He gave it a smack” (Dixon, 1991) Verbal expressions occasionally function as heads – “His giving money to the poor is commendable” (Pullum, 1991) Important to distinguish grammatical function from POS or phrasal form!
14 Representational Considerations – Modifier Adjectives, Numerals, Nouns and Verb Participles often function as pre-head modifiers – “the red ball” – “the two balls” – “the altitude restriction” – “the running bull” Prepositional Phrases & Relative Clauses typically function as post-head modifiers – “the book on the table” – “the book that I gave you” Important to distinguish grammatical function from POS or phrasal form!
15 Representational Considerations – Complement Few true complements in nominals – “The fact that you like me” Don’t consider “of” phrases complements of noun – “The father of John” – “of” is not optional – noun + “of” licenses complement, not noun (not even relational nouns) To the extent that they exist in nominals, complements do not project grammatical features! – Complements have their own set of grammatical features
16 Representational Considerations Specifier provides primary indication of definiteness – “the man” and “the men” “the” projects the definiteness feature definite “the def ” – “a man” but not “a men” “a” projects the definiteness feature indefinite “a” projects the number feature singular “a indef+sing ”
17 Representational Considerations Head provides primary indication of number – “the man” “man” projects the number feature singular “man sing ” – “books” (e.g., “I like to read books”) “books” projects the number feature plural “books” also projects the definiteness feature indefinite “books plur+indef ”
18 Representational Considerations Specifier provides primary indication of definiteness; Head provides primary indication of number – “the books” “the” projects the definiteness feature definite “books” can project the definiteness feature indefinite, however – The indefinite feature of “books” conflicts with the definite feature of “the” – Projection of the indefinite feature by “books” is blocked “books” projects the number feature plural “the def books plur ”
19 Representational Considerations To be grammatical, nominals typically require an indication of definiteness and number – “the” alone is ungrammatical because it lacks a number feature – “book” alone is ungrammatical because it lacks a definiteness feature – “books” alone is grammatical – indefinite & plural – “that” alone is grammatical – definite & singular – “a” alone is ungrammatical – why? Blocked by “one” (Pinker, 2000)?
20 Representational Considerations To be grammatical, nominals typically require an indication of definiteness and number – “a books” is ungrammatical because the number feature of “a” and “books” conflict Plural feature of “books” cannot override singular feature of “a” – “a few books” is grammatical – why? Plural feature of “few” and “books” overrides singular feature of “a” “a few” may be a special construction
21 Representational Considerations Is a person feature required for a subject nominal to be grammatical? Common view of subject-verb agreement – 3 rd Pers Sing Pres Tense – verb marked with “s” 3 rd Pers Sing Pres Tense is special – Non-3 rd Pers Sing Pres Tense – verb not marked All common and proper nouns treated as third person PersonNumber SingularPlural First (non-third)I sitwe sit Second (non-third)you sit Thirdhe sitsthey sit
22 Representational Considerations Alternative viewpoint – Noun + “s” (plural) Verb (unmarked) = plural agreement – Noun (unmarked singular) Verb + “s” = singular agreement PersonNumber SingularPlural First(ignore for now)we sit Non-first (second)you sit Non-first (default)he sitsthey sit
23 Representational Considerations 1 st Pers Sing Pres Tense verb agreement is special – “I” treated as first-person – exceptional agreement for this one pronoun – All common and proper nouns—tens of thousands—unmarked for person PersonNumber SingularPlural FirstI sitwe sit Non-first (second)you sit Non-first (default)he sitsthey sit
24 Representational Considerations Past-tense of “be” is regular – no first-person exception! PersonNumber SingularPlural FirstI waswe were Non-first (second)you were Non-first (default)he wasthey were
25 Representational Considerations Subjective and Objective Case – comp markers – Only a few pronouns are marked for case in English I, We, He, She, They (subjective) Me, Us, Him, Her, Them (objective) What about You? Ambiguous or unmarked? – Common and Proper Nouns are not marked for Case in English No evidence of case agreement for common and proper nouns – “The tall man likes the short man” Genitive – a spec marker, not a comp marker
26 Representational Considerations No grammatical evidence for neuter gender in English distinct from inanimate Only animate (or human) nouns have gender in English (exceptions for names of ships, construal of inanimates as animate, etc.) – “man” – male vs. “woman” – female – “child” – unspecified Evidence that animacy is a grammatical feature – The man i I gave t i the book – The book j I gave the man t j Primary difference is animacy!
27 Computational Implementation project definite predicted the man “the” projects an object specifier which projects an object referring expression “the” functions as the specifier of the object referring expression object referring expression ~ nominal bind index
28 Computational Implementation the man “man” projects an object head which is integrated as head of the object referring expression projected by “the” singular human male
29 Computational Implementation his book “his” projects a possessive object specifier which projects an object referring expression “his” functions as specifier of the object referring expression distinct bind indexes
30 Computational Implementation his book “book” projects an object head which is integrated as head of the object referring expression projected by “his”
31 Computational Implementation hers hers is nice hers are nice “hers” projects a pronoun object referring expression which projects a higher level pronoun object referring expression “hers” functions as specifier of the higher object referring expression head of higher object referring expression is implied number of higher referring expression is unspecified!
32 Conclusions Grammatical features are projected from heads, specifiers and modifiers within nominals Grammatical features may be redundant and may conflict without the nominal being ungrammatical – “a indef+sing few indef+plur books indef+plur ” – “the def books indef+plur ” Grammatical features may be unspecified without the nominal being ungrammatical – “yours def is sing-agree nice” vs. “yours def are plur-agree nice”
33 Conclusions Language is processed incrementally (serial, pseudo-deterministic) and interactively (parallel, context sensitive) Grammatical feature conflicts are accommodated via non-monotonic mechanisms of overriding and blocking – Monotonic unification mechanisms (e.g. HPSG) are inconsistent with overriding and blocking! Grammatical feature underspecification is accommodated via (semantic) construal processes
35 Representational Considerations Only posit grammatical features for which there is grammatical evidence – No solid grammatical evidence for third-person grammatical feature in English – No grammatical evidence that “the” is marked for number If “the” is functional head, how does number feature get projected to DP? – Extended projections a la Grimshaw (2000) – Dual heads a la Cann (2001) – “the” marked for number (Radford, 1997) – “the” checks number of complement (Radford, 2004)
36 Computational Implementation negative “no” projects an object specifier which projects an object referring expression “no” functions as the specifier of the object referring expression no airspeed or altitude restrictions
37 Computational Implementation “airspeed” projects an object head which is integrated as head of the object referring expression projected by “no” singularinanimate no airspeed or altitude restrictions
38 Computational Implementation The processing of “or” is delayed until the word after “or” is processed. “altitude” projects an object head. In the context of “or” and “airspeed”, “altitude” is conjoined with “airspeed” into a conjoined object head. The conjoined object-head overrides the previous object head. function overriding no airspeed or altitude restrictions
39 Computational Implementation function shifting “restrictions” projects an object head. In the context of an object head, the previous object-head is shifted into a modifier function so that “restrictions” can function as the head of the object referring expression plural (feature overriding) no airspeed or altitude restrictions