Author: Peter Fendrich
Date: 12:07:48 10/01/00
Go up one level in this thread
On October 01, 2000 at 11:01:22, Brian Richardson wrote: >On October 01, 2000 at 06:38:48, Uri Blass wrote: > >>On October 01, 2000 at 05:14:42, Mike Adams wrote: >> >>>On October 01, 2000 at 04:48:41, Uri Blass wrote: >>> >>>>On October 01, 2000 at 04:20:46, Mike Adams wrote: >>>> >>>>> I've noticed that pulsar thinks the doubled pawns are worth more than the >>>>>danger of exposing its castle. When its white and castles kingside this is >>>>>particular dangerous when it opens the H file especially if the rook is sitting >>>>>right there on H8. I'm not as concerned about the F and G files because I think >>>>>it can better defend these files but it can be very difficult to moblize the >>>>>pieces to defend the H file. Should i put a penalty in at 1.5 times the doubled >>>>>pawn bonus? >>>> >>>>Chess is not a simple game. >>>>There are cases when open h file is not dangerous inspite of castling in the >>>>king side and there are cases when open f file is dangerous. >>>> >>>>I think that it is impossible to answer your question because the right panelty >>>>for open file should be dependent in the rest of the evaluation. >>>> >>>>Uri >>> >>>yes but take a look at this position. pulsar is black and it plays Nxg3. >>> >>>[D] r1bq1rk1/ppp2p2/2n4p/3pP1pn/3P4/2P2NB1/P1P1B1PP/R2QK2R b KQ - 0 14 >>> >>> >>>I think there are some general rules that you dont open the H file with the >>>opponents rook on H8. Pulsar does have a king saftey function that tells it not >>>to advance its castle side pawns but in some positions it seems to like doing >>>that. Maybe i'm not doing it right i gave it penalties similar to what the >>>simple chess program does for advancing castled pawns but sometimes when it >>>advances one pawn I think it gets easier for it to advance another if it thinks >>>it messes with the opponents postion. That is another area i'll have to look >>>at. With a check extension and deeper search pulsar, now over 2250 icc blitz, >>>can get itself out of a lot of diffictulties but some things are just stupid and >>>in this case i need to build into the evaluate that NxG3 followed by G4 are >>>really bad. The question is how to do that in a narrow sense that does not give >>>it rules that are bad half the time. >>>The move sequence of the game was: .. NxG3 HxG3 G4 Qg2 Gxf3 Qxh6 and of course >>>its over. > >I assume you meant Qd2 (not g2) > >Getting it to see Gxf3 is bad is not easy to do. the material value >>>of the Knight distorts the search and particulary with nullmove its hard to see >>>at shallower depths like 5 or 6 even with check extensions. I'm trying the >>>positon at Gxf3 on different versions of pulsar to see how much depth it takes >>>to see that. So far with NUll move off it does the best and sees it at depth 6. > >I use the following penalties in Tinker (which may be somewhat extreme): > >KING_AH_NOPAWN_PENALTY 240 // Potential Trojan attack when king > // castled and no A/H pawns. > // asymmetric penalty must be enough > // to postpone P x (N or B) >KING_AH_ATTACK_PENALTY 120 // worse when opponent has 2xR + Q >KING_AH_OPEN_PENALTY 480 // worse when file completely open > >It is asymetric in that these are the penalties for Tinker, but I divide by 4 >when Tinker is the attacker. The "attack" and "open" penalties are cummulative >with the nopawn penalty. They are only added when the opponent has a rook or >queen on the open A/H file. The completely open is when the opponent has no >pawns on the A/H file either. > >Tinker finds gxf3 to be bad (-420) at 6 ply (when forced, it is mate in 5 >afterwards). > >>>A freind said he tried it with crafty and crafty had a hard time seeing that >>>Gxf3 is bad but I did not get to see that for myself. >> >>Crafty17.11 on a slow pentium200 has no problem to see in 3 seconds that gxf3 is >>losing. >> >>Crafty17.11 has also no problem to see after 68 seconds with the same hardware >>that the position after g4 Qd2 is bad for black(the score is 4.40 pawns for >>white at depth 9 for the move h5. >> >>The tactical mistake is g4 and there is no reason to push the pawns forward. >> >>I do not think that Nxg3 is a good idea but after Nxg3 hxg3 Kg7 I do not see a >>clear win for white. >> >>Uri First I found these penalties rather high but what are your material evaluation for one pawn? //Peter
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