Introduction to Computational Linguistics Eleni Miltsakaki AUTH Fall 2005-Lecture 5 1 Whats the plan for today? Brief review of
Chomskys hierarchy of languages Tree Adjoining Grammar Lexical Functional Grammar Head-driven Phrase Structure Grammar 2 Main points from last lecture
Chomsky hierarchy of languages Tree adjoining grammar Lexicalization Locality and recursion Substitution and adjunction Lexical Functional Grammar Constituent structure (c-structure)
Functional structure (f-structure) 3 A little more background on syntax and phrase structure Language has a finite set of symbols but gives the possibility of producing infinitely many sentences Our brains have finite capacity we need structure
patterns Phrase structure is basic to all grammars Words, phrases, sentences We obtain the meaning of an utterance from the meaning of its parts Syntax defines the way the combination takes place, i.e., it provides structure
4 Tests for phrases/constituents Substitutability I met a man. I met the man. I met John. Permutability
Pronominalizability I met John. I met him. 5 6
Features We need to specify that the subject and the verb need to agree in person and number If we put all this information in the rules, the rules become to complex Instead, we use features S NP(Per, Num) VP (Per, Num)
S NP(Agr) VP (Agr) 7 Feature structure in HPSG A feature structure is a set of pairs of the form [ATTRIBUTE value] ATTRIBUTE: an element of the set of features named ATT in the grammar (e.g., case, person
etc) value can be atomic (a string) or another feature structure 8 Examples of feature structures 9
Feature types Feature structures are of a certain type, written in italics Features are organized in hierarchies
10 Identity in HPSG Identity of values is marked with boxes 11
Valence and grammar rules Complements are specified as complex categories in the lexical representation There are also specific rules for head complement combinations
12 Representation of valence in feature descriptions A lexical entry consists of: 13
Head feature principle In a headed structure, the head features of the mother are identical to the head features of the head daughter
14 Linguistic generalizations in the type hierarchy Types are arranged in a hierarchy The most general type is at the top Information about properties of an object of a certain type are specified in the definition of the type
Subtypes inherit these properties Like an encyclopedic entry The upper part of the hierarchy is relevant to all languages (universal grammar) More specific types maybe specific for classes of languages or just one language 15
A non-linguistic example 16 Head complement schema Head complement schema + head feature principle
17 A simple example 18 General information about HPSG
19 Applications 20 Acknowledgements The introduction to HPSG is based on
Stefan Mullers introduction to HPSG at ESSLLI 2001. Many thanks to Stefan Muller for making the slides of his tutorial publicly available 21
Franchee: 1 year old tinkled in the potty and said "I pee pee." I called out "Prince Nicholas" and he said "Yes M'am?" Big smile! Krystal: My 3 year old told his dad to "come here, the refrigerator wants you"...
Tettonica delle placche o tettonica a zolle e' ilmodellosulladinamica della terra. Già da parecchio tempo prima della grande intuizione di Alfred Wegener ( F. Bacon nel 1620 e Buffon circa un secolo dopo) si erano notate le quasi perfette corrispondenze...
Most manors were self-sufficient, producing everything the people there needed. Most peasants never traveled farther than a few miles away during their entire lives. Life was harsh and short for the peasants. Everyone worked long hours, and few lived past...
Evaluating Agricultural Workplace Assistive Technology for Secondary Injury Hazards(An Assessment Tool for Professionals to Assist Farmers, Ranchers and Other Agricultural Workers with Disabilities). Pre-conference workshop, National AgrAbility Training. 2010, October 11, 2010. Charleston, West Virginia ...
A Cellular Automata Approach to Population Modeling Alexa M. Silverman Purpose To use cellular automata to model population growth and change To observe the effects of temperature on the behavior of populations To determine whether a cellular-based model of population...
Oceanic Zones - Open ocean zone . Is beyond the continental slope and contains 65% of the water in the ocean.. This zone is further divided into subzones. Euphotic zone or . Sunlit zone: photosynthesis take place here
"Waving His Wand at 'Beowulf'" by Ethan Gilsdorf, New York Times. J.R.R. Tolkien Biography, The Tolkien Society ... Beowulf is the earliest known written work in English. ... Hard edged things made by the blacksmith's hammer attack me.
What was the Korean War? The Korean War started on 25th June 1950 when over 90,000 North Korean soldiers launched an invasion of South Korea. It occurred during a time of debate over the future course of US foreign policy.
Ready to download the document? Go ahead and hit continue!