[computer-go] Remarks on the Indigo-Paper

[Don Dailey]

With Cilkchess, since we used cilk the parallel version was identical to
the single processor version (it would compile a serial version with no
extra trouble.)   Also, Cilk is such a great abstraction that we never
had to debug parallel issues.   We had performance bugs however, it was
difficult to determine on SMP machines when we were getting memory
contention.     

There is no need to answer to Apples and Trees unless you get into the
mood and decide you want to sometime.  Otherwise, don't worry.   I did
not intend to obligate you to respond. 

- Don

 

On Mon, 2006-06-19 at 15:20 +0200, Chrilly wrote:
> Dear Don,
> 
> >
> > Sometimes in alpha/beta searching you can compare search results.  This
> > was a real help when I did computer chess.
> Yes, but as you know from Cilkchess parallel code is not deterministic any 
> more. At least the Hydra search is not. This is a real pain in the ass. The 
> only thing I can do is to make at least the single-version relative stable. 
> Althought even there I detect sometimes bugs where I think afterwards: Why 
> has the programm ever played one reasonable game. But alpha-beta is a big 
> filter and one needs a lot of bugs or bad luck till it really produces 
> remarkable results. Cock de Gorter once joked about Diep: Its a great 
> programm, but it has too many bugs per second.
> 
> As a curiosity I won at the WC in 1993 a fantastic endgame against Rebel due 
> to a bug. Nimzo sacrificied the last piece - a knight - and won the 
> resulting pawn-endgame. Ed Schroeder tried for months to find a way to 
> implement this in Rebel. In fact it was the white/black bug. I had the rule: 
> If I have an unstopable passed pawn and the opponent has no piece to stop 
> it, give a big bonus.
> Due to the bug Nimzo checked for his own pieces and sacrificed the knight to 
> get this high bonus. When I told this Ed at the next AEGON he was really 
> relieved that no magic was behind this sacrifice. But it was the most 
> brilliant bug I know off.
> 
> Apples and Trees:
> I have not forgotten to answer you, but I am busy with programming and then 
> I am coming in a strange mood. Its certainly some sort of addiction. One 
> consequence is, that I am getting very narrow minded and "forget" everything 
> what is not related to programming. Please be still a little bit patient 
> with me.
> 
> Best Regards
> Chrilly
>