Intro¶

Basics for Common Sense Reasoning

Disambiguation¶

Earlier we had same frame for both below reports. We will try to disambiguate in this section.

Simpler Example

Thematic Role Systems¶

lexical analysis: each word in to lexical categories; Ashok is a noun, made is a verb syntatctic analysis: structure of sentence; Ashok is a noune phrase, made pan...griddle is a verb phrase etc. semantic analysis: Ashok was agent, made as action, pancakes object etc

semantic is served by lexical and syntactic

how do we know we understood the meaning? One could ask related questions, and we could infer right answers.

Note inferences may not be explicit in the sentence. For eg, who ate pancakes? David

System¶

Type of frame system.
An action or event would be identified by a verb (or did he say, just word?)
Example: Throwing - Who threw? What was thrown?
Might also expect a target specified by at, or destination by to. I threw at Ashok or I threw to Ashok.

Exercise¶

Note, we mentioned went as verb which is also ok.

Constraints¶

How do we know thos values? example, conveyance was by car?

Note, we need additional knowledge to categorize car as conveyance among 3 possibilities: agent, conveyance, location.

Resolving Ambiguity in Prepositions¶

Ontology tree

Note inferencing David as noun, went as verb, -- this is bottom up approach
From constraints, and ontology, we do a top down approach - take the "by", know its thematic role, use ontology, etc

So low level or bottom up triggers probes in to memory, which then returns knowledge like ontology, which then can be used for top down approach.

Ambiguity in Verbs¶

1)

I was wondering why ball was getting bigger and it hit me.
    hit is ambiguous
    hit could mean it occurred to me why ball was getting bigger
    hit could mean the ball literally hit me

2) Kleptomanics are those who steal things not for personal or financial gain but by irresistable urge

Its hard to explain puns to kleptomaniacs because they always take things literally
    take is ambiguous
    take could mean, they(kleptomaniacs) interpret the puns in literal sense
    take could also mean, kleptomaniacs steal things literally as a habit

take 11: to assume control

    David took control over the company

    agent: David
    target: Company
    particle: over

take 12: to remove from the body

    He took off his clothes from a body

    agent: He
    article: clothes
    particle: off

When we know background knowledge of candy,

With preposition from we could eliminate more

So the interpretation is to steal

Exercise: Resolving Ambiguity in Verbs¶

Back to Earthquake¶

Limitations¶

Note how we arrived at inference as "steal"

This was possible because of background knowledge of candy. Think of other sentences..

I took the candy for the baby
I took a toy from the baby
I took the medicine from the baby
I took the smile from the baby
I took a smile for the bay

More and more variations require more and more rules. Very hard to enumerate all the rules for all variations of sentences