Lexical-Functional Grammar A Formal System for Grammatical Representation Kaplan and Bresnan, 1982 Erin Fitzgerald NLP Reading Group October 18, 2006

10/18/2006Lexical-Functional Grammars LFG History  Developed by J. Bresnan and R. Kaplan in early 1970’s  Believed Chomskyan approach doesn’t model psychological reality of language  Other motivations: Supported in wider variety of languages than other formalisms (ex nonconfigurational languages with ~free word order/ case marks) Movement paradoxes:  That he was sick we talked about __ for days.  *We talked about that he was sick for days.  We talked about the fact that he was sick for days. “Syntax is not just structure-based”

10/18/2006Lexical-Functional Grammars How it’s different from Chomsky X’  Requires a higher level of mathematical precision  Subject, Object, etc considered primitives, not defined from positions in tree  Empty categories and funct. projections avoided  No movement  Unification-based  Levels of representation not strictly derived from each other  Not assumed that phonological, etc contents are derived from syntactic structure in any way.

10/18/2006Lexical-Functional Grammars How it’s different from HPSG  No hierarchical classification to deal with vertical and horizontal redundancy  LFG focuses on the processing and psychological reality of language  HPSG combines all syntactic, phonological, etc information into a single level

10/18/2006Lexical-Functional Grammars Generative Power of LFG  Not as powerful as general rewriting system or Turing Machine (LF languages are context-sensitive)  But, greater generative capacity than CFG (lower bound)  Allows a n b n c n, ωω non-CF languages  Sources of generative power: Functional Composition: Helps encode range of tree properties Equality Predicate: Enforces a match between properties encoded from different nodes

10/18/2006Lexical-Functional Grammars Correspondence Between Levels  C (onstituent) -structure: varies across languages  F (unctional) -structure: Universal properties  Structures aren’t isomorphic, but related by different correspondences stringc-structuref-structure discourse structure semantic structure φ σ π δ ?

10/18/2006Lexical-Functional Grammars C-Structure  Composed of Terminal strings Syntactic categories Dominance/precedence relations  Expressed through phrase structure trees  Determined by CF phrase structure rules  Regulated by a version of X’ theory

10/18/2006Lexical-Functional Grammars C-Structure S NPVP DETN NPVNDET N NP agirlhandedthebabyatoy S  NP VP ( ↑SUBJ)= ↓ ↑ = ↓ NP  DET N VP  V NP NP ( ↑ OBJ )= ↓ ( ↑ OBJ2 )= ↓ Immediate Domination Metavariables: ↑ : mother f-structure ↓ : self f-structure Immediate Domination Metavariables: ↑ : mother f-structure ↓ : self f-structure i.e. head Set specifiers: S  S CONJ S ↓є ↑ ↓є ↑ Adjuncts also use set indicators

10/18/2006Lexical-Functional Grammars F-structure  Composed of Grammatical function names Semantic forms Feature symbols  Models internal structure of language where grammatical relations are represented  Formalized through matrix of attributes, viewable as mathematical function  Lexical schemata determine content of lexical items

10/18/2006Lexical-Functional Grammars F-structure SUBJSPECA NUMSG PRED‘GIRL’ TENSEPAST PRED‘HAND ’ OBJSPECTHE NUMSG PRED‘BABY’ OBJ2SPECA NUMSG PRED‘TOY’

10/18/2006Lexical-Functional Grammars F-structure: Attributes and Values SUBJSPECA NUMSG PRED‘GIRL’ TENSEPAST PRED‘HAND ’ OBJSPECTHE NUMSG PRED‘BABY’ OBJ2SPECA NUMSG PRED‘TOY’

10/18/2006Lexical-Functional Grammars F-structure: Attributes and Values SUBJSPECA NUMSG PRED‘GIRL’ TENSEPAST PRED‘HAND ’ OBJSPECTHE NUMSG PRED‘BABY’ OBJ2SPECA NUMSG PRED‘TOY’

10/18/2006Lexical-Functional Grammars F-structure: Primitives SUBJSPECA NUMSG PRED‘GIRL’ TENSEPAST PRED‘HAND ’ OBJSPECTHE NUMSG PRED‘BABY’ OBJ2SPECA NUMSG PRED‘TOY’ Symbols Semantic Forms Embedded Structures

10/18/2006Lexical-Functional Grammars F-structure: Input to Semantic Interp SUBJSPECA NUMSG PRED‘GIRL’ TENSEPAST PRED‘HAND ’ OBJSPECTHE NUMSG PRED‘BABY’ OBJ2SPECA NUMSG PRED‘TOY’ AgentThemeGoal

10/18/2006Lexical-Functional Grammars C-Structure to F-Description S NPVP DETN NPVNDET N NP agirlhandedthebabyatoy S  NP VP ( ↑SUBJ)= ↓ ↑ = ↓ NP  DET N VP  V NP NP ( ↑ OBJ )= ↓ ( ↑ OBJ2 )= ↓ a: DET, ( ↑SPEC) = A girl: N, (↑NUM) = SG ( ↑NUM) = SG ( ↑PRED) = ‘GIRL’

10/18/2006Lexical-Functional Grammars C-Structure to F-Description S thebabya toy NP; ( ↑ SUBJ)= ↓ VP; ↑ = ↓ ( ↑OBJ) = ↓ NP ( ↑NUM) = SG ( ↑PRED) = ‘GIRL’ N ( ↑TENSE) = PAST ( ↑PRED) = ‘HAND<>’ V ( ↑SPEC) = A ( ↑NUM) = SG DET ( ↑OBJ) = ↓ NP ( ↑SPEC) = ↓ DET ( ↑NUM) = SG ( ↑PRED) = BABY N ( ↑SPEC) = ↓ ( ↑NUM) = SG DET ( ↑NUM) = SG ( ↑PRED) = TOY N agirlhanded f1f1 f2f2 f4f4 f5f5 f3f3 (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 3 TENSE) = past (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ Etc. f 1= f 3 (f 1 SUBJ) = f 2

10/18/2006Lexical-Functional Grammars F-Description to F-Structure  Locate Operator Obtain value for designator  Merge Operator (*Unify*) If left and right values exist, check if values are equal Else, create new entity (if properties are compatible) Similar to taking the union of two sets (if conflicts don’t exist)  Start clean; build until full f-description analyzed f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND<>’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’

10/18/2006Lexical-Functional Grammars F-structure f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1

10/18/2006Lexical-Functional Grammars F-structure: equations SUBJ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f3f3 f2f2

10/18/2006Lexical-Functional Grammars F-structure: equations SUBJ OBJ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f3f3 f2f2 f4f4

10/18/2006Lexical-Functional Grammars F-structure: equations SUBJ OBJ OBJ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f3f3 f2f2 f4f4 f5f5

10/18/2006Lexical-Functional Grammars F-structure: lexically derived eqns SUBJSPEC OBJ OBJ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f3f3 f2f2 f4f4 f5f5

10/18/2006Lexical-Functional Grammars F-structure: lexically derived eqns SUBJSPECA OBJ OBJ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f3f3 f2f2 f4f4 f5f5 MERGE CONFIRMED

10/18/2006Lexical-Functional Grammars F-structure: lexically derived eqns SUBJSPECA NUMSG PRED‘GIRL’ OBJ OBJ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f3f3 f2f2 f4f4 f5f5

10/18/2006Lexical-Functional Grammars F-structure: lexically derived eqns SUBJSPECA NUMSG PRED‘GIRL’ OBJSPECTHE NUMSG PRED‘BABY’ OBJ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f3f3 f2f2 f4f4 f5f5

10/18/2006Lexical-Functional Grammars F-structure: lexically derived eqns SUBJSPECA NUMSG PRED‘GIRL’ OBJSPECTHE NUMSG PRED‘BABY’ OBJ2SPECA NUMSG PRED‘TOY’ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f3f3 f2f2 f4f4 f5f5 MERGE CONFIRMED

10/18/2006Lexical-Functional Grammars F-structure: lexically derived eqns SUBJSPECA NUMSG PRED‘GIRL’ TENSEPAST OBJSPECTHE NUMSG PRED‘BABY’ OBJ2SPECA NUMSG PRED‘TOY’ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) = ‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f2f2 f4f4 f5f5

10/18/2006Lexical-Functional Grammars F-structure: lexically derived eqns SUBJSPECA NUMSG PRED‘GIRL’ TENSEPAST PRED‘HAND ’ OBJSPECTHE NUMSG PRED‘BABY’ OBJ2SPECA NUMSG PRED‘TOY’ f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) =‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f2f2 f4f4 f5f5

10/18/2006Lexical-Functional Grammars A Unique Solution? SUBJSPECA NUMSG PRED‘GIRL’ TENSEPAST PRED‘HAND ’ OBJSPECTHE NUMSG PRED‘BABY’ OBJ2SPECA NUMSG PRED‘TOY’ TONESOOTHINGLY f 1= f 3 (f 1 SUBJ) = f 2 (f 3 OBJ) = f 4 (f 3 OBJ2) = f 5 (f 2 SPEC) = A (f 2 NUM) = SG (f 2 NUM) = SG (f 2 PRED) = ‘GIRL’ (f 3 TENSE) = PAST (f 3 PRED) =‘HAND...’ (f 4 SPEC) = THE (f 4 NUM) = SG (f 4 PRED) = ‘BABY’ (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = SG (f 5 PRED) = ‘TOY’ f1f1 f2f2 f4f4 f5f5 Prefer minimal solution

10/18/2006Lexical-Functional Grammars Principles Regulating F-Structures  Uniqueness: Every attribute has a unique value  Completeness: Every function designated by a PRED must be present in the f-structure of that PRED  Coherence: (converse) Every argument in an f-structure must be designated by a PRED A string is grammatical only if it is assigned a complete and coherent f-structure, and its f-struct is consistent and determinate.

10/18/2006Lexical-Functional Grammars Principles Regulating F-Structures  Uniqueness: Every attribute has a unique value  Note: Uniqueness doesn’t prevent different attributes from sharing values A girl handed the baby a toys. (f 5 SPEC) = A (f 5 NUM) = SG (f 5 NUM) = PL (f 5 PRED) = ‘TOYS’

10/18/2006Lexical-Functional Grammars Principles Regulating F-Structures  Completeness: Every function designated by a PRED must be present in the f-structure of that PRED An f-structure is locally complete iff it contains all governable grammatical functions that its predicate governs. A girl handed. PRED ‘HAND ’ Lexical item requires governed functions OBJ and OBJ2

10/18/2006Lexical-Functional Grammars Principles Regulating F-Structures  Coherence: Every argument in an f-structure must be designated by a PRED An f-structure is locally coherent iff all governable functions are governed. The girl fell the apple the dog. PRED ‘FELL ’

10/18/2006Lexical-Functional Grammars Principles Regulating F-Structures  Uniqueness: Every attribute has a unique value  Completeness: Every function designated by a PRED must be present in the f-structure of that PRED  Coherence: (converse) Every argument in an f-structure must be designated by a PRED A string is grammatical only if it is assigned a complete and coherent f-structure, and its f-struct is consistent and determinate. Exception: Adjunct grammatical functions are not specified in PRED and no reqmt of mutual syntactic compatibility, so excluded from Uniqueness and Coherence Conditions

10/18/2006Lexical-Functional Grammars Changing structure, but not meaning S NPVP DETN NPVNDET N NP agirlhandedatoythebaby VP  V NP NP PP* ( ↑ OBJ )= ↓ ( ↑ OBJ2 )= ↓ ( ↑ ( ↓ PCASE ))= ↓ PP  P NP ( ↑ OBJ )= ↓ NP  DET N S  NP VP ( ↑ SUBJ)= ↓ ↑ = ↓ PP to P

10/18/2006Lexical-Functional Grammars Changing structure, but not meaning SUBJSPECA NUMSG PRED‘GIRL’ TENSEPAST PRED‘HAND ’ OBJSPECA NUMSG PRED‘TOY’ TOPCASETO OBJSPEC NUM PRED THE SG ‘BABY’ Dativizing Rule: ( ↑ OBJ2)  ( ↑ OBJ) ( ↑ OBJ)  ( ↑ TO OBJ) From ( ↑ ( ↓ PCASE))= ↓

10/18/2006Lexical-Functional Grammars Defining vs. Constraining Schema  Consider: The girl is handing the baby the toy. *The girl is hands the baby the toy. VP  V NP NP PP* VP’ ( ↑ OBJ )= ↓ ( ↑ OBJ2 )= ↓ ( ↑ ( ↓ PCASE ))= ↓ ( ↑ VCOMP )= ↓ VP’  (to) VP ↑ = ↓ is: V, ( ↑ TENSE) = PRESENT ( ↑ SUBJ NUM) = SG ( ↑ PRED) = ‘PROG ’ ( ↑ VCOMP PARTICIPLE) = PRESENT ( ↑ VCOMP SUBJ) = ( ↑ SUBJ) ( ↑ VCOMP PARTICIPLE) = c PRESENT Single, progressive arg Functional control Constraint Schema

10/18/2006Lexical-Functional Grammars Raising Verbs  The girl persuaded the baby to go.  The girl persuaded the baby that the baby (should) go.  Link via co-indexing, or arguments assumed distinct VP  V NP NP PP* VP’ ( ↑ OBJ )= ↓ ( ↑ OBJ2 )= ↓ ( ↑ ( ↓ PCASE ))= ↓ ( ↑ VCOMP )= ↓ VP’  to VP (↑TO) = ↓ ↑=↓ (↑INF)= ↓ ↑=↓ persuaded: V, ( ↑ TENSE) = PAST ( ↑ PRED) = ‘PERSUADE ’ ( ↑ VCOMP TO) = c + ( ↑ VCOMP SUBJ) = ( ↑ OBJ)

10/18/2006Lexical-Functional Grammars Raising Verbs  The girl promised the baby to go.  The girl promised the baby that the girl (should) go. VP  V NP NP PP* VP’ ( ↑ OBJ )= ↓ ( ↑ OBJ2 )= ↓ ( ↑ ( ↓ PCASE ))= ↓ ( ↑ VCOMP )= ↓ VP’  to VP (↑TO) = ↓ ↑=↓ (↑INF)= ↓ ↑=↓ promised: V, ( ↑ TENSE) = PAST ( ↑ PRED) = ‘PERSUADE ’ ( ↑ VCOMP TO) = c + ( ↑ VCOMP SUBJ) = ( ↑ SUBJ)

10/18/2006Lexical-Functional Grammars ( ↑ PARTICLE) = PASSIVE ( ↑ PRED) = ‘PROMISE ’ ( ↑ VCOMP TO) = c + ( ↑ VCOMP SUBJ) = ( ↑ BY OBJ) Raising Verbs: Passivization  The baby was persuaded to go by the girl.  *The baby was promised to go by the girl. persuaded: V, promised: V, ( ↑ PARTICLE) = PASSIVE ( ↑ PRED) = ‘PERSUADE ’ ( ↑ VCOMP TO) = c + ( ↑ VCOMP SUBJ) = ( ↑ SUBJ) Doesn’t conform to Fn Control Restrictions

10/18/2006Lexical-Functional Grammars F-Level Distinct from Semantics  No quantifier or VP scope specification  Raising vs. Equi Verbs (All have semantic role) The girl persuaded the baby to go. The girl expected the baby to go. Same f-structure, very different semantics

10/18/2006Lexical-Functional Grammars Long Distance Dependencies  The girl wondered [who the baby saw __].  Instance of constituent control  Decompose into chain of functional identities

10/18/2006Lexical-Functional Grammars Bound Domination Metavariables  Aim to provide a formal mechanism to represent long-dist constituent dependencies No unmotivated grammatical functions or features Allow unbounded # of controllees for single constituent Succinctly show generalizations

10/18/2006Lexical-Functional Grammars C-Structure for Long-Distance Dependencies thebabysaw ( ↑ Q-FOCUS)= ↓ ↓ = ▼ NP ↑=↓ S↑=↓ S ( ↑OBJ) = ↓ NP ( ↑PRED) = WHO N ↑= ↓ VP ( ↑SPEC) = ↓ DET ( ↑NUM) = SG ( ↑PRED) = BABY N ( ↑TENSE) = PAST ( ↑PRED) = ‘SEE<>’ V ( ↑OBJ) = ↓ NP who f1f1 ( ↑ SCOMP)= ↓ S’ e ↑=▲ NP Bounded Domination Metavariables: ▲ : bounded above (longer path) ▼ : bounding node Bounded Domination Metavariables: ▲ : bounded above (longer path) ▼ : bounding node

10/18/2006Lexical-Functional Grammars More Precisely  She’ll grow that tall/*height.  She’ll reach that *tall/height.  The girl wondered how tall she would grow/*reach ___.  The girl wondered what height she would *grow/reach ___.  These examples show that some bounding should be further constrained to specify POS Follow by AP Follow by NP (e: ↓ = ▼ AP ) (e: ↓ = ▼ NP )

Thanks!

10/18/2006Lexical-Functional Grammars More (unfinished) slides

10/18/2006Lexical-Functional Grammars Bounding Convention  A node M belongs to a control domain with root node R iff R dominates M and there are no bounding nodes on the path from M up to but not including R  Pg 245

10/18/2006Lexical-Functional Grammars Unification with Complex Expressions  See packet pg 10/22  Outside-in Combine feature structures at their roots and work top-down  Inside-out Begin with two distinct f-structs sharing a substructure, and recursively combine up Req’d for analyses like topicalization and anaphoric binding

10/18/2006Lexical-Functional Grammars Subject-Auxiliary Inversion in LFG  Pg 228  A girl is handing the baby a toy.  Is a girl handing the baby a toy?  *Is a girl is handing the baby a toy. Prevented by “distinctiveness of semantic form instances”

10/18/2006Lexical-Functional Grammars Generative Power of LFG  A c-structure derivation is valid iff No category appears twice in non-branching dominance chain No NT exhaustively dominates an optionality e At least one lexical item (or controlled e) appears between two optionality e’s derived by same rule element.

10/18/2006Lexical-Functional Grammars Proper Instantiation  Pg 246