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(1) Determine parameters to describe the characters of the target system.
(2) Express the relationship between the parameters with equations.
(3) Analyze these equations and get the number value.
When solving these kinds of behavior problems in motion system with
computer, the following three questions will be faced:
(1) Quite a lot of knowledge is required in Step (1) and (2), and corresponding
algorithms are also required.
(2) Properties in some target systems are difficult to express in mathematics
formulae.
(3) Step (3) can get number value, but the behavior of target system is not
distinct.
In order to solve the question (2) and (3), qualitative reasoning usually adopts
following analysis steps:
(1) Structure recognition: dividing target system into parts.
(2) Causality analyses: analyzing how target system spreads when input varies.
(3) Behavior reasoning: analyzing how the internal state changes in target system
when input varies with time.
(4) Function explanation: The result of behavior reasoning indicates the
behaviors of target system, which can explain the function of target system.
On the whole, the idea of qualitative reasoning can understood as:
(1) Grasp the main factor of the described target and neglect the secondary factor
in order to simplify the description of the problem.
(2) Disperse the parameter
) which varies continuously with time into
qualitative value set. Usually the qualitative value [
x
(
t
x
] of variable
x
is defined
as:
Í
,
if
x
<
0
[ ]
x
=
0 ,
if
x
=
0
Ë
Í
+
,
if
x
>
0
Ì
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