Hi Shlomi and Bill R.
Sorry, I just don't go along with you guys at all. Each position,
whether intermediate or not, is an entity unto itself, and is either
solvable or unsolvable. If a solver algorithm cares how the position was
arrived at, then it isn't properly designed.
Let me state it in a nontechnical, logical way:
For any original position, there is a tree of all possible moves. The
interstices of this tree each represent a position. What any solver does is
to pare down the full gross tree into its essentials. One essential task of
any practical solver is to eliminate all the branches of the tree which
repeat a position that has occurred somewhere on the path back to the
original position. So that the pared tree will contain each possible
position only once. Some paths lead to a solution, some paths lead to an
impossible position. The impossible positions are recognized only when all
possible paths further along have not led to a solution. Whether the scan
is depth-first or breadth-first, or whatever, the solver follows a process
where it works its way through the tree, and when any path leads to a blind
alley, it returns to a position for which it has not yet fully developed the
tree, and departs from there with a previous untried move.
Best regards, ----------------Adrian
Received on Wed Jun 26 2002 - 17:22:15 IDT