LINGUISTICA GENERALE E COMPUTAZIONALE

1. LINGUISTICA GENERALE E COMPUTAZIONALE CONOSCENZA LESSICALE:IL LESSICO GENERATIVO

2. Introduction • Lexicon— ideally collection of all words of a language • Information stored in a lexicon- • Phonetic information • pronunciation • Semantic information • meaning • Morphological information • transitivity and intransitivity (verbs) , count vs. mass (noun)

3. Lexicon (contd…) Example of “eat” in the Oxford Advanced Learner’s Dictionary eat /i:t/ v (pt ate /et/; pp eaten /i:tn/):1. sth (up) to food into the mouth,chew and swallow it: he was too ill to eat Pronunciation Meaning Morphological information Lexical entry

4. Mental Lexicon • Mental Lexicon: information stored in the mind of a native speaker • Native speakers store information • Phonetic information • pronunciation • Semantic information • meaning • Morphological information • transitivity vs.intransitivity (verbs), count vs. mass (noun) • Additional information • use of a word in a new context, syntactic environment of a word, word-formation rules

5. Example of Mental Lexicon • Example of eat in a native speaker’s mind • Pronunciation: long /i:/ is used in eat • Grammatical information: past tense is ate /et/ • Word-formation rules: /-s/ is the third person singular present tense marker as in • he eats • Meaning: 1. Take in solid food: she ate a banana • 2. Take a meal: we did not eat until 10 P.M. • 3. Worry or cause anxiety in a persistent way: what’s eating you up. • Syntactic Information: eat needs an agent to perform the action. • the agent role is obligatory.

6. Lexicon in Computational Linguistics • Lexicon meant for Natural Language Processing (NLP) must have the • following properties: • Morphological information • Parts of speech information • Rules should be there to deal with both regular and irregular forms • e.g ate (past tense of eat) • men (plural of man) • Semantic information • Can handle lexical ambiguity • Syntactic information • Action verbs will always have an agent

7. Polysemy and the Logical Problem of Polysemy Polysemy • An individual word can have indefinite number of subtle meaning difference • Natural Languages are highly polysemous • This creates ambiguity • Weinreich distinguishes between two types of ambiguity • Contrastive ambiguity • Complementary polysemy

8. Polysemy and the Logical Problem of Polysemy (contd…) Contrastive Ambiguity • A lexical item carries two distinct unrelated meanings • This is a case of homonymy • words spelled or pronounced in the same way but have different meanings Example: • bank a financial institution • bank place beside a body of water.

9. Complementary polysemy (1)a. Mary doesn’t believe the book. b. John sold his books to Mary. (2)a. Eno the cat is sitting on yesterday’s newspaper. b. Yesterday’s newspaper really got me upset. (3)a. Mary is in Harvard Square looking for the Bach sonatas. b. We won’t get to the concert until after the Bach sonatas. (4)a. I have my lunch in the backpack. b. Your lunch was no longer today than it was yesterday. (5)a. The phone rang during my appointment. b. My next appointment is John.

10. Sense Enumeration Lexicon (SEL) • WordNet and similar resources are examples of SENSE ENUMERATION LEXICA • Direct approach to handle polysemy is to allow the lexicon to have multiple listing of words, each annotated with a separate meaning or lexical sense. • Widely accepted in both computational and theoretical linguistics.

11. Sense Enumeration Lexicon (SEL) • Example of Contrastive Senses bank2 CAT= count-noun GENUS= shore bank1 CAT= count-noun GENUS= financial-institution

12. Newspaper1 CAT= count-noun GENUS= artefact Nominal polysemy in sense enumeration lexica • Newspaper Newspaper2 CAT= count-noun GENUS= information

13. Sense Enumeration Lexicon (SEL) • Possible Modification of Complementary Polysemy in SEL newspaper sense1 CAT= count-noun GENUS= artefact sense2 CAT= count-noun GENUS= information

14. Verbal polysemy in sense enumeration lexica Syntactic polysemy deals with polivalency (I), object deletion (II) and the general properties of argument expression (III). (I) a. Mary began to read the novel. b. Mary began reading the novel. c. Mary began the novel. (II) a. Mary ate (her meal) quickly. b. Mary devoured *(her meal) quickly. (III) a. John carved a doll (out of the wood). b. John carved the wood (into a doll).

15. GENERATIVE LEXICON THEORY • (Pustejovsky, 1991, 1995) • Claim: the concepts associated with a word in a context are GENERATED by a process starting from lexical entries structured into QUALIA STRUCTUREs and involving GENERATIVE DEVICES such as TYPE COERCION and CO-COMPOSITION

16. Generative lexicon theory: lexical entries A lexical entry in the generative lexicon consists of the following elements at least: • Argument Structure • True Arguments • Default Arguments • Shadow Arguments • True Adjuncts • Event Structure • Qualia Structure • Formal • Constitutive • Telic • Agentive

17. Argument Structure • True Arguments: syntactically realized parameters of the lexical item John arrived late • Default Arguments: logically present in the expressions but are not necessarily expressed syntactically. John built the house out of bricks • True Adjuncts: • modify the logical expression • part of the situational interpretation She drove down to New York on Tuesday.

18. Argument Structure (contd…) • Shadow Arguments:semantically incorporated in the lexical item and are expressed by discourse specification and contextual factors Mary buttered her toast • hidden argument is the material being spread on the toast • these are not optional arguments but expressible only under specific conditions • refer to the semantic content that is not necessarily expressed in syntax Example: Mary buttered her toast with margarine

19. SELECTION 1. a. The man fell/died. b. The rock fell/!died. a. John forced/!convinced the door to open. b. John forced/convinced the guests to leave. a. John poured milk into /!on his coffee. b. John poured milk into/on the bowl.

20. Integrating Selection into Grammars

21. CONSEQUENCE OF SELECTION: ONTOLOGICAL ASSUMPTIONS

22. BUT … • Unlike in other lexical theories, in GLT types can be modified via TYPE COERCION (see below)

23. Event Structure • event type of a lexical item and a phrase • events can be sub-classified into at least three sorts: State, Process and Transition Event Structure of build as found in the following expressions They are building a new house The house was built by John build EVENTSTR= E1= process E2= state

24. QUALIA ROLES Word meaning is structured on the basis of four generative factors, called qualia roles, that capture how humans understand objects and relations in the world and provide the minimal explanation for the linguistic behavior of lexical items. FORMAL: the basic category that distinguishes an object within a larger domain CONSTITUTIVE: the relation between an object and its constituent parts TELIC: the object’s purpose and function AGENTIVE: factors involved in the object’s origin or ‘coming to being’

25. novel const = narrative formal = book telic = reading agent = writing Qualia Qualia structures and argument polysemy Qualia Structure for novel

26. A generative device: type coercion • Type Coercion • a lexical item or phrase is coerced to a semantic interpretation by a governing item in the phrase, without changing its syntactic type Mary began to read the novel Mary began reading the novel Mary began the novel • Function Application with Coercion • different complement type of the verb • different interpretations of the verb that arise for the different complements

27. Other generative devices • Selective Binding • a lexical item or a phrase operates specifically on the substructure of a phrase, without changing the overall type in the composition a good knife: a knife that cuts well • Co-composition • multiple elements within a phrase behave as functors, generating new non-lexicalized senses for the words in composition John baked the potato John baked the cake

28. NOMINAL POLYSEMY A dot object is a deeper structure relating the apparently contradictory senses of the word. For each sense pair there is a relation that ‘connects’ the senses in a well-defined way. The dot object is characterized as: - a Cartesian type product of n types (the product τ1xτ2, of types τ1and τ2, each denoting sets, is the ordered pair <t1, t2>, where t1 ε τ1 ,t2 ε τ2) • with some additional constraints: there exists a relation R between the elements of τ1and τ2 , namely, R(t1, t2). This relation must be seen as part of the definition of the semantics for the dot object.

29. Type combinations included in the broad range of complex types encountered in natural language: a. phys_objinfo : e.g., book, record b. eventevent : e.g., construction, examination c. eventquestion : e.g., exam d. eventfood : e.g., lunch, dinner e. eventhuman : e.g., appointment For each of these type products, there is a unique relation, Ri, that structures the types. For example, nouns such as book or record, are structured by a containment relation R (container-like concepts). This containment relation -hold(x,y)- must be encoded directly into the semantics of the concept as the FORMAL quale value.

30. The lexical structure for newspaper as a dot object is represented as follows: newspaper ARGSTR = ARG1 = y:information ARG2 = x:phys_obj QUALIA = informationphys_obj FORM = hold(x,y) TELIC = read(e,w,xy) AGENT=write(e,v,xy) This translates to the following logical expression: λx yev[newspaper (x:physobj  y:info) hold(x,y) λwλe [read (e,w,xy)  [write(e;v,x y)]]

31. MORE FORMAL DETAILS

32. Three Ranks of Type Entities Events

33. System of Generating Types

34. Qualia are incorporated into Type Itself

35. Qualia as Types

36. Functional Selection

37. Functional Type Coercion

38. Co-composition

39. Coercion in Function Composition

40. Selection and Coercion

41. Type Specification

42. GLT AND LEXICAL RESOURCES

43. Generative lexicon vs. WordNet • Formal role is similar to the hypernymy relation • Constitutive role is similar to the meronymy relation • Nothing in WordNet like • the functionality link • Event structure • Exists in some WordNets, e.g., Hindi WordNet

44. LEXICAL RESOURCES BASED ON GLT • SIMPLE • LKB

45. SIMPLE • Lessico creato all’Universita’ di Pisa

46. some semantic types for abstract & concrete entities TOP TELIC ENTITY CONSTITUTIVE AGENTIVE ... ... Event Concrete_entity ... Representation Property • Living_entity • Human • Animal • Vegetal_entity • Artifact • Susbstance • Location • Food • Material Abstract_entity • Quality • Quantity • Physical_prop • Psychol_prop • ..... • Sign • Language • Information • ..... • Convention • Cognitive_fact • ..... Artifact • Furniture • Instrument • Clothing • Artwork Artifactual_material

47. some semantic types for events EVENT Phenomenon Aspectual Cause_change Psych_event ... State Act ... ... ... Change ... ... Creation Relational_state ... ... Relational_change Acquire_knowledge Non_relational_act Move Change_possession Natural_transition Cause_act Relational_act Speech_act Change_location ...

48. some semantic types for adjectives TOP Intensional Extensional Temporal Psychological_prop Relational_prop Social_prop Modal Emphasizer Physical_prop Intensifying_prop Emotive Manner Temporal_prop Object_related

49. Formal Constitutive Agentive Telic made_of is_a_follower_of has_as_member is_a_member_of has_as_part instrument kinship is_a_part_of resulting_state relates uses C O N S T I T U T I V E result_of agentive_prog agentive_cause agentive_experience caused_by source used_for used_as used_by used_against A G E N T I V E isa antonym_comp antonym_grad mult_opposition INSTRUMENTAL indirect_telic purpose TELIC created_by derived_from ARTIFACTUAL AGENTIVE is_the_activity_of is_the_ability_of is_the_habit_of ACTIVITY causes concerns affects constitutive_activity contains has_as_colour has_as_effect has_as_property measured_by measures produces produced_by property_of quantifies related_to successor_of precedes typical_of contains feeling DIRECT TELIC object_of_activity P R O P E R T Y is_in lives_in typical_location LOCATION Extended Qualia Extended roles Structure

50. Orthogonal dimensions of meaning Formal role is_a Telic role instrument Constitutive role is_made_of used_for created_by Agentiverole