Author: Uri Blass
Date: 05:06:13 11/11/04
Go up one level in this thread
On November 11, 2004 at 07:49:01, Richard Pijl wrote: >On November 11, 2004 at 02:51:31, Tony Werten wrote: > >>On November 10, 2004 at 22:27:03, Mike Byrne wrote: >> >>> 4. Rb1 Qc7 5. Ba4 (s=2) >>> 9 3.76 -1.64 1. Bc2 cxb4 2. axb4 a5 3. e4 Nc6 4. >>> bxa5 bxa5 5. Ra4 Qc7 >>> 9-> 7.25 -1.64 1. Bc2 cxb4 2. axb4 a5 3. e4 Nc6 4. >>> bxa5 bxa5 5. Ra4 Qc7 (s=3) >>> 10 10.03 -1.52 1. Bc2 cxb4 2. axb4 a5 3. bxa5 bxa5 >>> 4. Rg4 f6 5. Rxf4 exf4 6. gxf6 (s=2) >>> 10 25.95 -1.27 1. Nxe5 Qe8 2. Be4 cxb4 3. Nxf7 bxc3 >>> 4. Nh6+ Kg7 5. Bxc3+ Rf6 6. Bxf6+ Kf8 >>> 7. Bxb7 Qxe2# >>> 10-> 27.04 -1.27 1. Nxe5 Qe8 2. Be4 cxb4 3. Nxf7 bxc3 >>> 4. Nh6+ Kg7 5. Bxc3+ Rf6 6. Bxf6+ Kf8 >>> 7. Bxb7 Qxe2# >> >>If your mainline ends in a checkmate, with a -1.27 score, your biggest problem >>is not "How fast does it solve the position" > >Checkmate will always lead to a stand-pat choice in qsearch. Any move will get >your king taken, so better do nothing and return eval instead. :-) >Easily solved with check-evasions in qsearch, but of course that costs some >nodes. >Richard. No need to do check evasions in qsearch to solve the problem. My first movei had no checks and check evasion in qsearch but it always knew that checkmate is checkmate based only on the evaluation function. Having evaluation that detect checkmates can save nodes because you do not need to search captures at checkmate position. In most cases it is also cheap to find that the last move threats no check so there is no checkmate. Note that in the case of movei generating all the legal moves is part of the evaluation function so it can also detect stalemates. It is one of the main reasons that movei is not a fast searcher and I probably need to replace my mobility evaluation by something better. Uri
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