Derek Nalls wrote on Mon, May 26, 2008 07:36 PM EDT:
Rest assured, I intend to drop this futile topic of conversation soon and
leave you alone.
The following is my impression of how the limited randomization of
move selection that you have described as being at work within Joker80
must be harmful to the quality of moves made (on average) at long
time controls. Since you have experience and knowledge as the
developer of Joker80, I will defer to you the prerogative to correct
errors in my inferred, general understanding of its workings.
_______________________________________________________
short time control
1x
At an example time control of 10 seconds per move (average),
Joker80 cuts thru 8 plies before it runs out of time and must
produce a move. At the moment the time expires, it has selected 12
high-scoring moves as candidates out of a much larger number of
legal moves available. Generally, all of them score closely together
with a few of them even tied for the same score. So, when Joker80
randomly chooses one move out of this select list, it has probably not
chosen a move (on average) that is beneath the quality of the best
move it could have found (within those severe time constraints)
by anything except a minor amount. In other words, the damage to
playing strength via randomization of move selection is minimized
under minimal time controls.
___________________________
long time control
360x
At an example time control of 60 minutes per move (average),
Joker80 cuts thru 14 plies (due to its sophisticated advance pruning
techniques) before it runs out of time and must produce a move.
At the moment the time expires, it has selected only 4 high-scoring
moves as candidates out of a much larger number of legal moves
available. Generally, all of them score far apart with a probable
best move scored significantly higher than the probable second best
move. So, when Joker80 randomly chooses one move out of this
select list, the chances are 3/4 that it has ignored its probable best
move. Furthermore, it may not have chosen the probable second best move,
either. It just as likely could have chosen the probable third or fourth
best move, instead. Ultimately, it has probably chosen a move
(on average) that is beneath the quality of the best move it may have
successfully found by a moderate-major amount. In other words,
the damage to playing strength via randomization of move selection is
maximized under maximal time controls.
_______________________________________
The moral of the story is that randomization of move selection reduces
the growth in playing strength that normally occurs with time and plies
completed.