CSC485/2501
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November 26, 2021
∣∣∣ Computer Science
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Semantics vs agreement
Gap and Movement
Semantic head driven generation
(Beta reduction and quantifier)
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Agreement (agr)
Grammatical features of words.
Examples: number, case, aspect, tense, person . . .
In English, nouns have two types of number: singular and plural.
Should be used to control what sentence can be generated and what should be rejected.
Semantics (sem)
The ”meaning” of words.
Both cat and cats should have the same sem: cat.
For this assignment, count means the actual count of the thing(s).
Usually can’t be used in controlling what sentence can (not) be generated/rejected.
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The Active Voice
The goalie kicked the ball.
The goalie
sem:(kick, agent:goalie, theme:ball)
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The Passive Voice
The ball was kicked.
sem:(kick, agent:?, theme:ball)
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The Passive Voice
The ball was kicked.
sem:(kick, agent:?, theme:ball)
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Semantic Head Driven Generation: TLDR
TLDR: Replace cat> with sem head> on all the semantic heads.
An NP’s semantic head is the N.
A VP’s semantic head is the V.
A CLP semantic head is the CL.
An S semantic head is the VP.
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Semantic Head Driven Generation: Basic Idea
gen(s, sem:(kick, agent:goalie, theme:ball)).
Top-down or buttom-up generator: too slow to traverse all of the possible rules.
However, we can utilize the fact that the semantics (sem) of the semantic head is
exactly the same as the product (left hand side).
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