Information Technology Reference
In-Depth Information
Fig. 10.3
A spatial representation of a slide
10.2
The Role of a Model
Newell and Simon's problem-space is defined by means of linguistic (propositional)
representations and the manipulation of linguistic representations to solve problems.
This has stimulated the development of animated and automated sentence manip-
ulators (the logic research program). However, scientific and engineering thinking
uses other vehicles to model that should not be regarded as reducible to just sets of
sentences.
As an illustration of what is outside the philosophy of the logic research program,
consider the process of designing a simple slide as shown in Fig.
10.3
. Such a slide
may form part of the transportation system for a product in a factory. This product
will have specific dimensions, weight and composition. After the drawing of a sketch
that shows the spatial relationship of the components of the slide, it is required to
determine the acceleration of the product down the slide so that the velocity may be
calculated at its point of reception.
Reference is now made to the theory of Dynamics. In a wider context, a theory
in this paper does not necessarily mean a formal theory. Any set of statements that
forms some coherent description of the world that can be used to “render facts
likely” (Peirce
1934
) will be considered a theory. A theory, for example, is a set of
propositions that reduces the uncertainty in the world for an agent. Some aspects of
the theory of Dynamics (Newtonian Mechanics) may be presented as such a series
of statements thus:
T1. Every Body travels in a straight line unless a force acts upon it.
T2. Momentum is the product of mass and velocity.
T3. Force is the rate of change of momentum.
T4. For every action, there is an equal and opposite reaction.
T5. Gravity is an acceleration caused by the mutual attraction of mass.
T6. Weight is a force due to gravity.
T7. Forces (and hence velocities) will add as vectors.
