Author: James Swafford
Date: 12:09:42 05/27/04
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On May 27, 2004 at 14:35:54, Uri Blass wrote: >On May 27, 2004 at 07:39:37, milix wrote: > >>Hello! >>Chess enging bugs (CEBUGS) are very different than normal bugs (BUGS). They are >>very good in hiding from debuggers. They are also very good in covering one >>another so the engine seems to behave normaly, except if it plays a very >>important match. Sometimes CEBUGS are very productive and when they are >>eliminated the engine's strength drops about 50-150 points. Of course they have >>to be eliminated otherwise the engine cannot deliver a mate in KQvsK or it >>always thinks that passed pawns are Gods. CEBUGS are also layered and they are >>very cooperative. In the first layer we have the evaluation bugs (usualy + >>instead of -). In the next layer we can find search bugs (improper alpha - beta >>windows, or wrong score sign or null-move bugs). In the final layer we meet the >>most powerful bugs ever, the transposition table bugs. These bugs have a stealth >>ability, they are protecting the bugs in the first two layers while their >>actions mimic the behaviour of an evaluation term or a search property (like >>failing low). >> >>I am sure that other bugs exists in my engine but I haven't had the honor to >>meet them yet. >> >>PS: In the Null-Move search you might have forgotten to clear the ep-square as >>well as to restore it. This bug is very easy to detect and fix. But if you have >>forgotten to update the hash signature (if you encode ep square in the hash >>signature) then you are very lucky. You have met a Predator-like bug. > >I did some progress in making my book code(it is still not ready at this moment) >and I can describe some bugs in the process: > >1)I asked the computer to print the moves in the book only to discover that >printf("%s %s",move1,move2) does not work. Are move1 and move2 char* 's? If so, that should be fine. What's happening? -- James > >The only way to print strings correctly is by seperate printf for different >strings. > >2)I discovered that all the hash keys that I remembered in the book were 0 >Reason:I tried to write the moves in the book too early >and I wrote them before I initialized my zob keys. > >3)To check that after the correction they are correct I tried to use setmask >that is array of all the powers of 2 but it did not work. > >Reason:I initialized setmask only after creating my book. > >I had also some bugs when I tried to write a function to do binary search in an >array but hopefully I got rid of them. > >Now I need to translate the array to a file and have a code for binary search in >a file that will work in a similiar way. > >Uri
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