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Computational language: week 9

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

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Computational language: week 9

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  1. 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

  2. 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

  3. 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

  4. Finite State Automata • Deterministic FSAs • Non-deterministic FSAs • An FSA with decision points • Self-loop may be in a particular state • Arcs may have εtransitions

  5. Finite State Automata • Formal language • Set of strings • Finite symbol set, alphabet

  6. 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

  7. 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

  8. 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

  9. 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

  10. 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

  11. 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 • c:c a:a t:t +N:εPL:s

  12. Finite state transducers and word structure • Finite State Transducers for morphological parsing • Boundary markers: • ^ morpheme boundary • # word boundary

  13. 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#

  14. 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:#

  15. Knowledge representation • Linguistic knowledge • Linguistic facts • Relations between linguistic facts • Computable

  16. Knowledge representation • Linguistic knowledge • Linguistic facts • lexicon • Relations between linguistic facts • Computable

  17. Knowledge representation • Linguistic knowledge • Linguistic facts • lexicon • Relations between linguistic facts • inference • default inference • Computable

  18. Knowledge representation • Linguistic knowledge • Linguistic facts • lexicon • Relations between linguistic facts • inference • default inference • Computable • DATR • Prolog

  19. Knowledge representation and the lexicon • Inheritance hierarchy

  20. Knowledge representation and the lexicon • Inheritance hierarchy • A graphical representation of how facts or properties are shared amongst entities

  21. Knowledge representation and the lexicon • Inheritance hierarchy

  22. Knowledge representation and the lexicon • Inheritance hierarchy

  23. Knowledge representation and the lexicon • Inheritance hierarchy

  24. Knowledge representation and the lexicon • Default inheritance hierarchy

  25. Knowledge representation and the lexicon • Default inheritance

  26. Knowledge representation and the lexicon • Default inheritance

  27. Knowledge representation and the lexicon • Default inheritance

  28. Knowledge representation and the lexicon • Default inheritance

  29. Knowledge representation and the lexicon • DATR, lexical knowledge representation language • Inference and default inference • Compiled in Prolog • Developed by Evans and Gazdar • Network Morphology

  30. Knowledge representation and the lexicon • DATR demonstration

  31. Lexical knowledge representation Summary • Inheritance • Inference rules • Formalism • Computable

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