Page 164 - DCAP310_INTRODUCTION_TO_ARTIFICIAL_INTELLIGENCE_AND_EXPERT_SYSTEMS

Introduction to Artificial Intelligence & Expert Systems

Notes Schank developed the model to represent knowledge for natural language input into computers.
Partly influenced by the work of Sydney Lamb, his goal was to make the meaning independent
of the words used in the input, i.e. two sentences identical in meaning, would have a single
representation. The system was also intended to draw logical inferences.
The model uses the following basic representational tokens:

real world objects, each with some attributes.
real world actions, each with attributes
times

locations
A set of conceptual transitions then act on this representation, e.g. an ATRANS is used to represent
a transfer such as “give” or “take” while a PTRANS is used to act on locations such as “move” or
“go”. An MTRANS represents mental acts such as “tell”, etc.
A sentence such as “john gave a book to Mary” is then represented as the action of an ATRANS
on two real world objects John and Mary.

This representation is used in natural language processing in order to represent them earning of
the sentences in such a way that inference we can be made from the sentences. It is independent
of the language in which the sentences were originally stated. CD representations of a sentence
is built out of primitives, which are not words belonging to the language but are conceptual,
these primitives are combined to form the meanings of the words. As an example, consider the
event represented by the sentence.

In the above representation, the symbols have the following meaning:
Arrows indicate direction of dependency

Double arrow indicates two may link between actor and the action
P indicates past tense
ATRANS is one of the primitive acts used by the theory. It indicates transfer of possession

0 indicates the object case relation
R indicates the recipient case relation
Conceptual dependency provides a structure in which knowledge can be represented and also a
set of building blocks from which representations can be built. A typical set of primitive actions
are:
ATRANS – Transfer of an abstract relationship (E.g.: give)
PTRANS – Transfer of the physical location of an object (E.g.: go)

PROPEL – Application of physical force to an object (E.g.: push)
MOVE – Movement of a body part by its owner (e.g.: kick)

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