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Lecture 19 Word Meanings II
CSCE Natural Language Processing Lecture 19 Word Meanings II Topics Description Logic III Overview of Meaning Readings: Text Chapter 189NLTK book Chapter 10 March 27, 2013
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Overview Readings: Text 19 NLTK Book: Chapters 9 and 10
Last Time (Programming) Wordnet overview Today Computational Semantics Feature based grammars Readings: Text 19 NLTK Book: Chapters 9 and 10 Next Time: Computational Lexical Semantics
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HW review Dropboxes Soon to exist: NER for handbook
frequency distribution - Handbook Assignment Regular Expression /urllib2 - Identify prerequisites Assignment Extend backoff tagger to include trigram Assignment Test1
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Wordnet Most synsets are connected to other synsets via a number of semantic relations. These relations vary based on the type of word, and include: Nouns hypernyms: Y is a hypernym of X if every X is a (kind of) Y (canine is a hypernym of dog) “superordinate” “superclass” hyponyms: Y is a hyponym of X if every Y is a (kind of) X (dog is a hyponym of canine) “IS-A” coordinate terms: Y is a coordinate term of X if X and Y share a hypernym (wolf is a coordinate term of dog, and dog is a coordinate term of wolf) “sibling” holonym: Y is a holonym of X if X is a part of Y (building is a holonym of window) “HAS-PART” meronym: Y is a meronym of X if Y is a part of X (window is a meronym of building) “IS-PART” “IS-MEMBER”
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Verbs Adjectives Adverbs
hypernym: the verb Y is a hypernym of the verb X if the activity X is a (kind of) Y (to perceive is an hypernym of to listen) troponym: the verb Y is a troponym of the verb X if the activity Y is doing X in some manner (to lisp is a troponym of to talk) entailment: the verb Y is entailed by X if by doing X you must be doing Y (to sleep is entailed by to snore) coordinate terms: those verbs sharing a common hypernym (to lisp and to yell) Adjectives related nouns similar to participle of verb Adverbs root adjectives
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x
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Wordnet online Fig 19-1
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Word senses A word sense is a distinct meaning
Synonym sets are relations among word senses couch/sofa, car/automobile antonyms also long/short, big/large, rise/fall extremes; or opposite in direction
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Fig 19-2 Noun relations in wordnet
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Fig 19-3 Verb relations in wordnet
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Fig19-4-like IS-A (hyponym) Chain for lemma bass#7
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Sister terms (= coordinate terms)
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Thematic Roles 19.19 “Sasha broke the window.”
exists e,x,y breaking(e) & breaker(e, Sasha) & brokenThing(e, y) & window(y) 19.20 Pat opened the door. Deep or thematic roles Panini (Indian grammarian) circa 7th-4th century BC Fillmore 1968, Gruber 1965
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Fig 19.5 Common Thematic Roles
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19.6 Examples of Thematic Roles
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Variations of expression
John broke the window. John broke the window with a rock. The rock broke the window. The window broke. The window was broken by John.
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Case Frames for verbs Break Agent: Subject, Theme:Object
Agent: Subject, Theme:Object, Instrument: PP-with Instrument:Subject, Theme:Object Theme: Subject
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19.4.3 Problems with Thematic Roles
Example 19.27 the cook opened the jar with the new gadget. the new gadget opened the jar. Example 19.28 Shelly ate the banana with a fork. *The fork ate the banana.
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Prop Bank PropBank is a corpus that is annotated with verbal propositions and their arguments—a "proposition bank".
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PropBank Online
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FrameNet
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Framenet Core Roles
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FrameNet Examples ... [Cook the boys] ... GRILL [Food their catches] [Heating_instrument on an open fire]. [Avenger I] 'll GET EVEN [Offender with you] [Injury for this]! [ Punishment This attack was conducted] [Support in] RETALIATION [ Injury for the U.S. bombing raid on Tripoli... [Sleeper They] [Copula were] ASLEEP [Duration for hours]
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FrameNet Index of Lexical Units
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Selectional restrictions of roles from PropBank
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Fig 19-7 Hamburger Edible?
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Figure 19.8 Shank’s Conceptual Dependencies
Roger Schank 1969 Professor at Yale aclweb.org/anthology-new/C/C69/C pdf
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Conceptual Dependency
Governing Categories PP – an actor or object corresponds to concrete nominal nouns ACT – an action LOC – a location of a conceptualization T – time of a conceptualization Assisting Categories PA – attribute of a PP AA – attribute of an ACT Graphical representation aclweb.org/anthology-new/C/C69/C pdf
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Conceptual syntax rules
Ref: ??? Elaine Rich’s Text on AI
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CD Examples John ran. John is tall. John is a doctor. A nice boy.
John’s dog John pushed the cart John took the book from Mary John drank milk john fertilized the field the plants grew Bill shot Bob
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CD for “John at the egg.” .
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CD “John prevented Mary from giving the book to Bill.”
.More tenses and modes p past f future t transition k continuing c conditional / negative ? Interrogative pil present
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Restaurant Script Roger Schank again
Collection of scenes describing typical events e.g. “visit a restaurant” Entering Ordering Eating Paying/Leaving
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Modifiers
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