Information Technology Reference
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Fig. 6.11 The Chinese Ring puzzle. Top: classic version, provided by the Puzzle Museum (used
with permission) of a classic version. Bottom: plastic version with the same search space, and
slightly different state description and different operators (the knobs turn on a piece of plastic that
slides in a track)
The Chinese Ring puzzles in Fig. 6.11 are like this. The puzzle on the top has the
rings as actual rings, the puzzle on the bottom has a knob as a ring. The task is easy
once you figure out what moves are possible and how close you are to the goal of
removing the rings. A problem where you don't know or can't easily see the state
of the system is also ill-defined. Most versions of the Chinese Ring puzzle also are
difficult because you can't tell what the state is very easily; this is particularly true
for the top puzzle in Fig. 6.11 .
Ill-structured problems can be difficult because you do not know what the goal
is or how close you are to the goal. Knowing how close you are to a solution is a
problem for both of these Chinese puzzle versions. Tetris is pretty well structured;
Rubik's cube is well structured, but users have trouble judging the state because it
is so complex. Installing software can become very ill structured quickly if the
error messages are not clear. Learning where you are in Rubik's cube or what
software is not installed and is causing the error both improve problem solving.
Designers can help users with ill-structured problems in several ways. It is
easier for users if the operators are clear. Thus, menus or lists of actions they can
take help define the problem space. This list can also indicate what the constraints
are on choosing operators. Having a clearly defined goal and good guidance
towards the goal are also helpful. These distinctions can be modified or inverted
for games and creative pursuits. Making problems less clear can make them more
interesting and make the process of solving them a more creative experience.
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