TREE ADJOINING GRAMMAR AN INTRODUCTION TO TREE ADJOINING GRAMMAR Rajat Kumar Mohanty 11/16/2018

Basics of TAG Formalism Operations Constraints Tree Families OUTLINE XTAG System Basics of TAG Formalism Operations Constraints Tree Families Feature Structure 11/16/2018

2. XTAG SYSTEM What does it do? It takes a sentence as input, and provides: Constituency (NP, VP, PP, etc.) Derivational History (how phrases are combined) Predicate/ Argument Structure (main verb, subject, object, etc) 11/16/2018

XTAG System: An Overview Input Sentence Morph Analyzer POS Tagger Morph DB Stat. DB POS Blender Trees DB Syn DB Tree Selection Tree Grafting Derivation Structure Source: The XTAG Research Group, 2001 11/16/2018

Diverse Linguistic Resources Subcategorization information (argument structure) Syntax of various constructions (specific transformations) Frequency information Morphological information 11/16/2018

A Tree Adjoining Grammar (TAG) consists of a quintuple (, NT, I, A, S)  is a finite set of terminal symbols; NT is a finite set of non-terminal symbols:   NT = ; S is a distinguished non-terminal symbol: S  NT; I is a set of finite trees, called initial trees; A is a finite set of finite trees, called auxiliary trees. 11/16/2018

I: Initial Tree S like NP0 VP V NP1  like 11/16/2018

A: Auxiliary Tree S yesterday Ad S* yesterday 11/16/2018

Operations in Tree Adjoining Grammar Substitution The substitution operation appends one tree at a frontier node of another tree. That is substitution takes place at non-terminal nodes on the frontier side, which are marked for substitution by a down arrow. 11/16/2018

Substitution NP John N John NP Mary N Mary S  NP0 VP V NP1 N N John saw Mary S saw NP0 VP V NP1  saw 11/16/2018

The adjunction operation is more powerful. It can be used to insert one tree within another. A new tree is built from an auxiliary tree  and a tree  ( : initial, auxiliary or derived) by adjunction. 11/16/2018

Adjunction S  NP0 VP V VP has V NP1 bought S bought NP0 VP 11/16/2018

Adjoining Constraints Selective Adjunction: The adjunction of an auxiliary tree is not mandatory on the given node. Null Adjunction: It disallows any adjunction on the given node. Obligatory Adjunction: In this case, the adjunction of an auxiliary tree is mandatory. 11/16/2018

Derivation in Tree Adjoining Grammar Derived Tree Derivation Tree 11/16/2018

Derived Tree in TAG S  Ad S NP0 VP N V NP1 N Yesterday John saw Mary 11/16/2018

John (1) Mary (2.2) yesterday (0) Derivation Tree in TAG saw John (1) Mary (2.2) yesterday (0) 11/16/2018

Declarative Intransitive Tree Family [Tnx0V] Sr [ ] nx0V [ ] NP0 [ ] VP [ ] V< > The intransitive verbs (e.g., sleep, dance, etc. )select this Tree family [Tnx0V]. 11/16/2018

Ergative Tree Family [TEnx1V] Sr [ ] nx1V [ ] NP1 [ ] VP [ ] V< > The ergative verbs (e.g., sink, melt, etc. )select this Tree family [Tnx1V]. 11/16/2018

Declarative Transitive Tree Family [Tnx0Vnx1] Sr [ ] nx0Vnx1 [ ] NP0[] VP [ ] V< > NP1 [ ] The transitive verbs (e.g., eat, like, hit, etc. )select this Tree family [Tnx0Vnx1]. e.g., I ate an apple. 11/16/2018

Declarative Ditransitive Tree Family [Tnx0Vnx1pnx2] Sr [ ] nx0Vnx1pnx1 [ ]   NP0 [ ] VP [ ] V< > NP1 [ ] PP2 [ ] The di-transitive verbs (e.g., put, usher, etc. )select this Tree family [Tnx0Vpnx1]. e.g.,The secretary ushered me into his office. 11/16/2018

Transitive Tree with Object NP Extraction [Wnx1nx0Vnx1] This problem, I solved.   St [ ] [ ]   NP1 [ ] Sr [ ] NP0 [ ] VP[ ] V< > NP1 [ ] NA  11/16/2018

Transitive Tree with object Wh-NP Extraction [Wnx1nx0Vnx1] What did he eat?   Sq [ ] [ ]   NP1 [ ] Sr [ ] NP0 [ ] VP[ ] V< > NP1 [ ] NA  11/16/2018

Sentential Complement Tree: [Tnx0Vnx1s2] S r [ ] nx0Vnx1s2 [ ] NP0[ ] VP [ ] V<> NP1[ ] S2*[ ] John told Mary that it was his turn. John begged Mary to increase his disk quota. 11/16/2018

Complementizer Tree: [sCOMP] mode: <2> ind / inf   COMP [comp: <1> ] Sr* [assign-comp: <1>] [comp: <>] mode: <2> comp: nil assign-comp: <> John told Mary that it was his turn. John begged Mary to increase his disk quota. 11/16/2018

Suggested Readings Joshi, A. K. 1987. An Introduction to Tree Adjoining Grammars. In A. Manaster-Ramer, ed., Mathematics of Language. Amsterdam: John Benjamins. XTAG Research Group. 1999. A Lexicalized Tree Adjoining Grammar for English. Technical Report IRCS, University of Pennsylvania, Philadelphia. 11/16/2018