Re: richard?

[John Williams <williams@morinda.com>]

On Thu, 31 May 2001, Benjamin Good wrote:
> anybody here from richard lately?  i sent him a message couple days ago and 
> i haven't heard back from him, which is unusual, unless he is travelling, 
> which is not unusual.
> 
> incidentally, the message is about an undo, me n zeke are trying to undo 
> thoughtwave 167, but we get an error message 'attempt to undo unsuccessful, 
> we apologize for the inconvience.'  we've tried it several times, w/ both of 
> us submitting the original undo request.  i've never seen this before on the 
> server, so i don't know what to make of it.  anybody know anything about it?

The technique used to undo moves is not foolproof.  Basically, it replays
the game from the beginning, and stops 1 move early.  If there is a
significant element of randomness, or if there is not enough information
in the saved move strings, or even if the game cannot parse its own move
string, the undo will fail with the above message.  I haven't looked at
thoughtwave to determine exactly what is wrong, but here are some examples
from other games:

Backgammon:  undo works because the rolls are in the move string, but
after undoing, the new roll may be different.
Chess:  if you move Bxc4 and bxc4 is possible at the same time (pawn vs
bishop), the undo will fail because the move string parser is not case
sensitive.
Scramble:  has significant randomness.  The game saves the previous board
state, and overrides the undo function to restore it.  You can only undo
one previous move in scramble.
Chex,Dots:  cannot undo at all.

~ John Williams