Re: computer-go: perfect play

[Don Dailey <drd@xxxxxxxxxxxxxxxxxxxxx>]

   Isn't there still a problem?

   People play in different ways....
   The game works in different ways..,....

   Surely there's a possibility that a tree gives two equal solutions ( it
   happens quite often depending how you do the analysis... there's more than
   just the binary tree )...

   Sorry...
   That didn't explain anything...

   Depending upon your opponent there are different 'better' moves...

   Who/How are you playing...
   ( another point for consideration being as I'm a ludicrous amateur, doesthe
   progression ever change and is there ever anything that's perfect..? )...

   Yet another side issue would be if we had a computer version that was
   apparently 'perfect' then surely it should play different moves based on
   the ability and style of the opponent...

   Is there a perfect move?

   Regards,
   Mike...



Hi Mike,

A lot  of this  discussion  is more  theoretical  than  practical.  In
practical terms, most players  will play the move  that gives them the
best  chances, as far as  they  can judge.   This may involve "playing
risky", playing careful,  playing provocatively or whatever suits your
style of play and your own  personal strengths and ideosyncracies.  In
chess you  get players who love  high risk sacraficial play and others
who play  very careful and  "boring" and  it's  very much a matter  of
personality.

But in theoretical terms, a move  is either "optimal" or "non-optimal"
and it has nothing to do with style of play or personality.

An optimal move is the very best move you can make, a move "God" would
make so to speak.  We of course are using the term "GoGod" to describe
a machine which plays perfect Go and we  are assuming that GoGod plays
fair, he doesn't read your mind or take  advantage of the fact that he
knows you  can't handle a  certain type of position  very well.  GoGod
doesn't have  a definite playing style  either, he just plays the most
efficient move possible.  He doesn't care that he  might beat you much
quicker by playing another  move because you  probably won't answer it
correctly, he just assumes that you will  play best too.  GoGod thinks
you are as smart as he is.
 
GoDevil is just as smart  as GoGod and  cannot beat GoGod, but neither
can GoGod beat him.  But GoDevil does have a  definite style and it is
to trick you by whatever means he can.   He tries to take advantage of
any weakness  he knows  or suspects  you have.   Even though this will
work very well  against you and me,  it won't fool GoGod.  GoGod  will
just calmly respond  by playing the  best move possible,  as he always
does.

I would like to  note  that in  many positions,  there may be  several
optimal moves which you alluded to, in which case  you can just choose
one at  random, or choose based on  whatever criteria makes you happy.
They are all the same in principle, but  of course some of those moves
may be harder to refute (by a fallible opponent that is) than others.

What makes all  of this discussion  theoretical Mike, is  that only in
relatively simple positions can we tell with any certainty which moves
are really optimal or not.

Don