Author: James T. Walker
Date: 22:29:25 11/27/00
Go up one level in this thread
On November 27, 2000 at 15:18:49, Christophe Theron wrote: >On November 26, 2000 at 13:08:36, Ed Schröder wrote: > >>On November 26, 2000 at 11:00:08, Christophe Theron wrote: >> >>>On November 25, 2000 at 02:47:29, Uri Blass wrote: >>> >>>>On November 24, 2000 at 23:22:04, Christophe Theron wrote: >>>> >>>>>On November 24, 2000 at 17:02:11, Uri Blass wrote: >>>>> >>>>>>You can see in the Rebel board that the problem of infinite time is known. >>>>>> >>>>>>I found the problem when I analyzed a position for a long time. >>>>>> >>>>>>My experience is that the time is dependent on the position and I had examples >>>>>>when the time was less than 3 hours on my PIII450(192 mbyte hash) >>>>>> >>>>>>I had also an example when the time per move was more than 6 hours and in this >>>>>>case I did not try to check if the inifinite is finite. >>>>>> >>>>>>Uri >>>>> >>>>> >>>>> >>>>>Yes, I am sorry for this one. I have found the bug now, and it works OK. I have >>>>>a computer here that is computing on your position, Uri, since 69 hours and 30 >>>>>minutes and is still thinking (BTW it wants to play h4 at depth 21, score is >>>>>+0.38, now computing depth 22). >>>>> >>>>>I guess we will provide a free update to solve this issue. >>>>> >>>>> >>>>> >>>>> Christophe >>>> >>>>Thanks for the information. >>>> >>>>The position is from a game in the final of the championship of Israel in >>>>correspondence games. >>>> >>>>GM Abir Har Aven(ICCF rating 2585) is against me. >>>> >>>>Abir (white) started 1.g3 d5 2.f4 h5 3.Nf3 >>>> >>>>I already played h4 and it is Abir to move. >>>>I find that tiger plays h4 with the plan h4 Nxh4 Rxh4 but after giving tiger >>>>the position after h4 Nxh4 it wants to play e5 with a different score(more than >>>>+1 after a few minutes). >>>> >>>>I expect Abir to play Nxh4 and I will have to decide if to play e5 or Rxh4. >>>> >>>>Uri >>> >>> >>> >>>Tiger has computed depth depth 22 after 1.g3 d5 2.f4 h5 3.Nf3 and score is now >>>0.44. Main line begins with: h4 Nxh4 e5 Nf3 exf4 gxf4 Ne7 e3 Nf5 d4 Ng3... >>> >>>It has been computing for 105 hours now, so I think the bug is definitely fixed. >>> >>> >>> Christophe >> >> >>105 hours huh... :) >> >>I remember a bug in Rebel (I believe it was Rebel7) which was baptized >>internally as the "24 hour bug". The case was that at random after exactly >>24 hours when the program was launched Rebel stopped to compute further >>without seeing that on the screen. It was already a pain to find this out, >>fixing wasn't so easy too and testing required to be after the screen >>exactly 24 hours after Rebel7 had been started and see if the bug was >>solved now by watching the debug information on the screen. All in all >>it took about a month to fix the "24 hour bug". >> >>But the nightmare wasn't over as a chess program also has something we >>call the permanent brain and also here the 24 hour bug was an issue. Same >>procedure only this time things went faster as the problem history was >>known. >> >>In total 2-3 lines in the program had changed still it caused about >>5-6 weeks to mark the bug as "solved". Just wonderful. >> >>Ed > > > >The "infinite time is finite" problem has been easier to find in Tiger. However >being sure it is fixed has indeed taken several days. > >The problem was a 32 bits node counter. This counter was here since the 286 >ages, and had never caused any harm. But nowadays, with 900MHz computers and >faster, the 32 bits counter overflows in a few hours, and it caused the program >to stop thinking!!! > >In a few years from now, I think I'll have to watch the NPS counter. Could it be >that this 32 bits counter could overflow? That would mean the program would >compute more than 2G nodes per second!!! :) > > > > Christophe It will not be very long. I have seen 600 Kn/s on my Athlon 900. Wait till the Pentium IV is out. Jim
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