process can be traced. As will be shown in the next section,
MAP-Q combines forward reasoning, backward reasoning,
and constraint processing. This display may not be the best
way to explain the solution to a person, but it is beneficial
for the further development of the system since it embodies
a cognitive approach allowing analysis of the systems
reasoning in comparison with the human problem-solving
process. It is reported that the method of problem solving
by humans also combines forward and backward reasoning
[1], and such a display of processing flow is necessary for
future studies.
The rules introduced in MAP-Q are shown in Table
1. As the examples of rule description of previous geomet-
rical systems, rules of Okamotos CAI system for geomet-
rical problems [12] represent operations of adding new
relations to the semantic network of geometrical objects. In
Chous geometrical proof system [2], rules about the areas
and the length of sides are given. Rules in these systems
mainly treat static relations about the sides and the angles
in a figure. In order to solve problems of quadratic func-
tions, however, rules for describing dynamic relations, such
as the locus or area of a movable point, are required. In the
MAP-Q system described in this paper, move and
moveif rules are introduced for handling movable points,
and operate1, operate2, and limit rules are intro-
duced for explicit call of expression transformation pro-
gram. These rules enable the solution of high-level
problems that cannot be treated by the previous rule de-
scription.
Rules that are provided to MAP-Q are not specific to
the solution of the problems of quadratic functions. Some
rules deal with figures and others with formulas. In the case
of figure-related rules (contact, move, moveif, cross, en-
close), the application conditions are specified so that the
rules can also be applied to link nodes connected to quad-
ratic curve object nodes. The scope of problems supported
Table 1. Rules given to MAP-Q
Link node Conditions for application Results obtained
contact curve and line touch one another expression for tangent
move point moves along line or curve coordinates of point
point moves along line or curve expression for line or curve
moveif point moves within certain area area of movement for another point represented
with same parameters
cross two lines intersect coordinates of crossing point
curve intersects line or another curve coordinates of crossing point (or multiple points)
on line passes through two points expression for line
line with known gradient passes through point expression for line
enclose area is enclosed by parabola and line expression for area
midpoint two points given middle point
min line segment or area given minimum value
max line segment or area given maximum value
ratio two line segments or two areas are given ratio
always-equal equality is given conditions for equality
parallel two lines are parallel one lines gradient
vertical two lines are perpendicular one lines gradient
quad four points make rectangle rectangles area
tri three points make triangle triangles area
operate1 calculation using one variable is given calculated result
operate2 calculation using two variables is given calculated result
distance two points are given distance between points
point and line are given distance from point to line
limit inequality is given conditions for inequality with respect to some
variable
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