Inteligenta Artificiala
Universitatea Politehnica Bucuresti
Anul universitar 2005-2006
Adina Magda Florea
http://turing.cs.pub.ro/ia_06
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Curs nr. 13
Prelucrarea limbajului natural
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Comunicare
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Definite
mesaj, limbaj, protocol
Componentele comunicarii
– intentie
– generare
– sinteza
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–
–
–
perceptie
analiza
desambiguare
incorporare
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Acte de comunicare
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Teoria actelor de comunicare
locutie
ilocutie
prelocutie
Tipuri de agenti care comunica
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–
–
–
–
–
–
asertive
directive
comisive
permisive
prohibitive
declarative
expresive
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Definire limbaj
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Lexicon
Analiza lexicala
Gramatici
Analiza (pars oratoris)
Terminale, neterminale, reguli de rescriere
simbol de inceput
LHS  RHS
Analza semantica
Analiza pragmatica
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Lexicon
Noun  breeze | wumpus | ball
Verb  is | see | smell | hit
Adjective  right | left | smelly …
Adverb  here | there | ahead …
Pronoun  me | you | I | it
RelPronoun  that | who
Name  John | Mary
Article  the | a | an
Preposition  to | in | on
Conjunction  and | or | but
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Gramatica
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Neterminale – diferite categorii din
propozitie
– sentence S
– noun phrase NP
– verb phrase VP
– prepositional phrase PP
– relative clause RelClause
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Exemplu
S  NP VP | S Conjunction S
NP  Pronoun | Noun | Article Noun |
NP PP | NP RelClause
VP  Verb | VP NP | VP Adjective |
VP PP | VP Adverb
PP  Preposition NP
RelClause  RelPronoun VP
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Analiza sintactica
– top-down parsing
– bottom-up parsing
– in adancime
– pe nivel
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Top-Down Parsing
"John hit the ball"
1. S
2. S  NP, VP
3. S  Noun, VP
4. S  John, Verb, NP
5. S  John, hit, NP
6. S  John, hit, Article, Noun
7. S  John, hit, the, Noun
8. S  John, hit, the, ball
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Bottom-Up Parsing
1. John, hit, the, ball
2. Noun, hit, the, ball
3. Noun, Verb, the, ball
4. Noun, Verb, Article, ball
5. Noun, Verb, Article, Noun
6. NP, Verb, Article, Noun
7. NP, Verb, NP
8. NP, VP
9. S
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Definite Clause Grammar (DCG)
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Gramatici BNF - probleme
Utilizare LP
Gramatici cu clauze definite
DCG – gramatica; propozitie = clauza
definita
neterminal = predicat de 1 argument
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In BNF
S  NP VP
In LP
NP(s1)  VP(s2)  S(Append(s1, s2))
NF
Noun  ball | book
In LP
(s = “ball”  s = “book”)  Noun(s)
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BNF, DCG, Prolog
BNF
FOPL
PROLOG
S  NP VP
NP  Noun
Noun  stench
Noun  wumpus
VP  Verb
Verb  smells
Verb  kills
NP(s1)  VP(s2)  S(append(s1,s2))
Noun(s)  NP(s)
Verb(s)  VP(s)
(s = “stench”  s = “wumpus”) 
Noun(s)
(v = “smells”  v = “kills”) 
Verb(v)
sentence([S1, S2]) :np(S1), vp(S2).
np(S):- noun(S).
vp(S):- verb(S).
noun(stench).
noun(wumpus).
verb(smells).
verb(kills).
?- sentence([wumpus,
smells]).
?-sentence([S1, S2]).
Imbogatire DCG
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Imbogatesc neterminale cu argumente
suplimentare
Verifica corectitudinea gramaticala
Ataseseaza semantica
Adauga expresii / functii care se
testeaza
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Argument pt semantica
DCG
FOPL
PROLOG
S(sem)  NP(sem1) VP(sem2)
{compose(sem1, sem2, sem)}
NP(s1, sem1)  VP(s2, sem2) 
S(append(s1, s2)),
compose(sem1, sem2, sem)
slide urmator
semantica compozitionala
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The dog has legs.
The ball is yellow.
The ball is red.
The dog bites.
(dog parts legs)
(ball property yellow)
(ball property red)
(dog action bytes)
sentence(S, Sem) :- np(S1, Sem1), vp(S2, Sem2), append(S1, S2, S),
Sem = [Sem1 | Sem2].
np([S1, S2], Sem) :- article(S1), noun(S2, Sem).
vp([S], Sem) :- verb(S, Sem1), Sem = [action, Sem1].
vp([S1, S2], Sem) :- verb(S1,_), adjective(S2, Sem1), Sem = [property, Sem1].
vp([S1, S2], Sem) :- verb(S1,_), noun(S2, Sem1), Sem = [parts, Sem1].
noun(dog,dog).
noun(ball,ball).
verb(bytes,bytes).
verb(is,is).
verb(has,has).
adjective(yellow,yellow).
adjective(red,red).
Verificare corectitudine gramaticala
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cazuri
subcategorii verbe: compleentul pe care
il poate accepta un verb
acord subiect predicat
etc.
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Parametrizarea neterminalelor
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Cazuri
Nominativ (subjective)
I take the bus
You take the bus
He takes the bus
Eu iau autobuzul
Tu iei autobuzul
El ia autobuzul
Acuzativ (objective)
He gives me the book
Imi da cartea
S  NP(Subjective) VP
NP(case)  Pronoun (case) | Noun | Article Noun
//
I
VP  VP NP(Objective)
//
believe him
VP  VP PP
// turn to the right
VP  VP Adjective
VP  Verb
PP  Preposition NP(Objective)
Pronoun(Subjective)  I | you | he | she
Pronoun(Objective)  me | you | him | her
sentence(S) :- np(S1,subjective), vp(S2),
append(S1, S2, S).
np([S], Case) :- pronoun(S, Case).
np([S], _ ) :- noun(S).
np([S1, S2], _ ) :- article(S1), noun(S2).
pronoun(i, subjective).
pronoun(you, _ ).
pronoun(he, subjective).
pronoun(she, subjective).
pronoun(me, objective).
pronoun(him, objective).
pronoun(her, objective).
noun(ball).
noun(stick).
article(a).
article(the).
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Subcategorii verbe
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Lista de subcategorii: ce complemente
accepta verbul
depinde de verb
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S  NP(Subjective) VP(subcat)
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dar cazuri in care nu depinde
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VP(subcat)  VP(subcat) PP
| VP(subcat) Adverb
I smell the wumpus now
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VP(subcat)  {subcat = np} VP(np) NP(Objective)
| {subcat = adj} VP(adj) Adjective
| {subcat = pp} VP (pp) PP
| Verb
smell
[NP]
[Adjective]
[PP]
smell a wumpus
smell awfull
smell like a wumpus
is
[Adjective]
[PP]
[NP]
is smelly
is in box
is a pit
give
[NP, PP] give the gold in box to me
[NP, NP] give me the gold
died
[]
died
S  NP(Subjective) VP(subcat)
NP(case)  Pronoun (case) | Noun | Article Noun
Pronoun(Subjective)  I | you | he | she
Pronoun(Objective)  me | you | him | her
VP(subcat)  {subcat = np} VP(np) NP(Objective)
| {subcat = adj} VP(adj) Adjective
| {subcat = pp} VP (pp) PP
| Verb
| VP(subcat) PP
| VP(subcat) Adverb
sentence(S) :- np(S1,subjective), vp(S2),
append(S1, S2, S).
np([S], Case) :- pronoun(S, Case).
np([S], _ ) :- noun(S).
np([S1, S2], _ ) :- article(S1), noun(S2).
VP(subcat)  VP(subcat) … !!!
vp(S, Subcat) :- Subcat = np, vp1(S1, np),np(S2, objective),
append(S1, S2, S).
vp1([S],np):-verb(S).
verb(give).
verb(make).
vp(S,Subcat) :- vp1(S1, Subcat), pp(S2), append(S1, S2, S).
Analiza pragmatica
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Analiza semantica
Desambiguare
Interpretare pragmatica – utilizare si
efect asupra ascultatorului
Indexical - situatia curenta
Anafora – deja mentionate
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Ambiguitate
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Lexicala
Sintactica
Referentiala
Pragmatica
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