Computational language: week 9 Finish finite state machines FSA’s for modelling word structure...
-
date post
20-Dec-2015 -
Category
Documents
-
view
214 -
download
0
Transcript of Computational language: week 9 Finish finite state machines FSA’s for modelling word structure...
Computational language: week 9 Finish finite state machines
FSA’s for modelling word structure Declarative language models
knowledge representation and inheritance non-monotonic or ‘default’ inheritance and
lexical knowledge representation multiple inheritance DATR: a lexical knowledge representation
language
Finite State Automata Deterministic FSAs
An FSA whose recognition behaviour is fully determined by the state it is in and the input symbol it is looking at
Finite State Automata Deterministic FSAs
An FSA whose recognition behaviour is fully determined by the state it is in and the input symbol it is looking at
Non-deterministic FSAs An FSA with decision points
Finite State Automata Deterministic FSAs Non-deterministic FSAs
An FSA with decision points Self-loop may be in a particular state Arcs may have ε transitions
Finite State Automata Formal language Set of strings Finite symbol set, alphabet L(m) = {baa!, ba!, baaa!,…}“formal language characterised by m”
m = model L = formal language
Finite State Automata Formal language Set of strings Finite symbol set, alphabet L(m) = {baa!, ba!, baaa!,…} A formal language models a
fragment of a natural language
Finite state transducers and word structure FSA for word structure
Handles the morphotactics Arc labels drawn from sets of lexical
classes Lexical entries and affixes in the
lexicon Achieve morphological recognition
Finite state transducers and word structure Finite State Transducers for
morphological parsing distinction between surface level and lexical level
lexical level includes basic stem and morphosyntactic features
cat +N+PL -> cats
Finite state transducers and word structure Finite State Transducers for
morphological parsing distinction between surface level and lexical level
lexical level includes basic stem and morphosyntactic features
cat +N+PL -> cats FST: maps one of set of symbols onto
another
Finite state transducers and word structure Finite State Transducers for
morphological parsing distinction between surface level and lexical
level lexical level includes basic stem and
morphosyntactic featurescat +N+PL -> cats FST: maps one of set of symbols onto
another c:c a:a t:t +N:εPL:s
Finite state transducers and word structure Finite State Transducers for
morphological parsing Boundary markers:
^ morpheme boundary # word boundary
Finite state transducers and word structure Finite State Transducers for
morphological parsing Boundary markers:
^ morpheme boundary # word boundary
c:c a:a t:t +N:εPL:^s#
Finite state transducers and word structure Finite State Transducers for
morphological parsing Boundary markers:
^ morpheme boundary # word boundary
c:c a:a t:t +N:εPL:^s# g:g o:e o:e s:s e:e +N:εPL:#
Knowledge representation Linguistic knowledge Linguistic facts Relations between linguistic facts Computable
Knowledge representation Linguistic knowledge Linguistic facts
lexicon Relations between linguistic facts Computable
Knowledge representation Linguistic knowledge Linguistic facts
lexicon Relations between linguistic facts
inference default inference
Computable
Knowledge representation Linguistic knowledge Linguistic facts
lexicon Relations between linguistic facts
inference default inference
Computable DATR Prolog
Knowledge representation and the lexicon
Inheritance hierarchy A graphical representation of how
facts or properties are shared amongst entities
Knowledge representation and the lexicon
Inheritance hierarchy BIRD:
wings = yes flies = yes eggs = yes feathers = yes
Seabird: food = fish Landbird:
food = insects
Knowledge representation and the lexicon
Inheritance hierarchy BIRD:
wings = yes flies = yes eggs = yes feathers = yes
Seabird: food = fish Landbird:
food = insects
Seagull Goldfinch
Knowledge representation and the lexicon Inheritance hierarchy
BIRD:
wings = yes flies = yes eggs = yes feathers = yes
Seabird: food = fish Landbird:
food = insects
Seagull Goldfinch
Penguin?
Knowledge representation and the lexicon
Default inheritance hierarchy BIRD:
wings = yes flies = yes eggs = yes feathers = yes
Seabird: food = fish Landbird:
food = insects
Seagull Goldfinch
Penguin: flies = no
Knowledge representation and the lexicon
Default inheritance
NOUN: singular = plural = s
Count_noun Noncount_noun:
plural = undefined
Book Sand
Cat
Knowledge representation and the lexicon
Default inheritance
NOUN: singular = plural = s
Count_noun Noncount_noun:
plural = undefined
Book Sand
Cat
Ox?
Knowledge representation and the lexicon
Default inheritance
NOUN: singular = plural = s
Count_noun Noncount_noun:
plural = undefined
Book Sand
Cat
Ox: plural = en
Knowledge representation and the lexicon
Default inheritance
NOUN: singular = plural = s
Count_noun Noncount_noun:
plural = undefined
Book Sand
Cat
Ox: plural = en
Goose: plural = geese
Knowledge representation and the lexicon
DATR, lexical knowledge representation language
Inference and default inference Compiled in Prolog Developed by Evans and Gazdar Network Morphology