Representation: An Introduction

Why Representation?

Tasks: going from inputs (stimuli) to outputs (responses)
The most primitive solution: a lookup table which specifies an output for every input
The problem with lookup tables:
There may be too many inputs to store (the world is continuous, after all). There is a need for the system to be able to respond appropriately to novel inputs.
The alternative solution: a function from inputs to outputs
- AI is about these functions: what they might look like for tasks requiring "intelligence".
- The functions may be very complex, requiring one or more transformations of the input, internal representations.

Are they explicit (directly interpretable), or are they in a form that looks like garbage to an outside observer (even though they serve their function for the system)?
Are they localized (in one place), or are they distributed throughout the system?
Are they propositional (language-like), or are they in some other form, for example, more like images?
Are they static or dynamic? Do they just sit there or do they "happen"?
Are there different kinds of representations for different domains that have little in common with each other?

Distinction between objects and relations
Wholes consisting of parts, which are in turn wholes consisting of parts: recursive structure
Slots (roles) and fillers (values)
- In an object, the COLOR slot may have filler GREEN and the FUNCTION slot may have filler CONTAINING_FOOD.
- In an event, the AGENT slot may have filler TYLER and the INSTRUMENT slot may have filler SCISSORS3.
Truth and falsehood
Generality (abstraction)
- The generalization (concept) TURNIP is an abstraction over all turnips, including, for example, TURNIP4.
- The generalization (concept) BORROW is an abstraction over all instances of borrowing, including, for example, BORROW8, in which Shelby borrowed a pair of scissors from Tyler.

What sort of evidence do we have for what the internal representations of cognition look like?
What about the input and output themselves? What form do they take?
How do representations relate to the world, to perception, and to action?

Last updated: 11 January 1996
URL: http://www.indiana.edu/~gasser/Q351/representation1.html
Comments: gasser@salsa.indiana.edu
Copyright 1996, The Trustees of Indiana University