Page 201 - Deep Learning

184 Adaptation

in terms of goal-situation-action triplets is known as the Production Systems
Hypothesis and it was first proposed by H. A. Simon and A. newell. 22
Unlike a proposition, a rule is neither true nor false. A rule of action is like
a piece of advice or an exhortation, with the difference that rules are typically
known only implicitly and hence not available for introspection. A rule is more
or less useful, more or less appropriate in that the action it recommends may
or may not lead to the goal, or may lead to the goal with greater or lesser cost
or effort, under the given circumstances. We can talk about the correctness of
rules only in the sense of efficiency vis-à-vis goal attainment, and efficiency is
a matter of degree. Unlike declarative knowledge, practical knowledge is goal
and task specific. techniques for sailing a ship are not much use when drawing
a map, and vice versa.
A single production rule does not suffice for even the simplest task. The
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strategy for making a cup of tea, for example, might contain as many as a hun-
dred rules. The set of all rules that are relevant for a task constitutes the per-
son’s practical knowledge of how to do that task. if a rule is an atom of practical
knowledge, a rule set is a molecule. There are many words in English that refer
to cognitive units of this latter sort: algorithm, heuristic, know-how, method,
plan, procedure, program, recipe, strategy, tactic, technique, trick, and so on.
For consistency, i will use the word “strategy.“ table 6.1 shows a hypothetical
strategy (rule set) for the everyday task of using an elevator.
Strategies are of various types. There are highly general but vague strategies
like, if you don’t know how the device works, just push any button and see what hap-
pens. others are very specific: if you need to use an ATM, look for a bank. Some
strategies are codified and learned explicitly. The standard procedures for arith-
metic taught in primary school are perfect examples. other methods are implicit
and more flexible. Cooking is a good example. Recipes are explicit but cooking
skills are nevertheless largely implicit. Sometimes implicit knowledge is said to be
tacit or intuitive. Some strategies, like the rules for using an elevator, are simple
and small in scope, while others, like the management skills needed to run an
international company, are complicated and vast in scope. Unfortunately, there
are few naturalistic studies of strategies and there is no widely accepted classifica-
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tion. A rule set is an idealization, but a useful idealization. The next question is
how a set of independent rules generates coherent and organized task behavior.

Strategy Execution
For a set of rules to produce overt behavior, some goal must be posed, the
current situation assessed, the most promising option (rule) selected, and the