Author: Rick Bischoff
Date: 05:24:45 10/19/04
I am still struggling with my huge node count in WAC #Iforgotthenumber-- anyway, I am trying out lazy evaluation, e.g., only counting material and seeing if I can get a cutoff from there.. Here is the code in the evaluation function: //int x = whiteScore - blackScore; //extern bool wtm; //if ( !wtm ) x = -x; //if ( x + 200 <= alpha ) return alpha; //else if ( x - 200 >= beta ) return beta; When this code is off, as shown above, I have the following stats from a depth-7 search: 6 157 295 112333 1. Ne5 Qxb3 2. Nxd7+ Kc8 3. axb3 Kxd7 4. Rxa7 7 153 1132 397249 1. Ne5 Qxb3 2. Nxd7+ Kc8 3. axb3 Kxd7 4. Rxa7 Nd5 1294061 nodes (1041179, 0.804583) 31.162 seconds (41526.9 NPS) 4000 nullmove try 1330 nullmove succeed (%33.25) OK, so when I turn on the lazy evaulation: 6 53 403 198712 1. Ne5 Rf6 2. Bg5 Qxb3 3. axb3 Re6 7 141 1720 752626 1. Ne5 Qxb3 2. axb3 Bxb5 3. Nxg6 Nxg6 4. Be3 move Ne5 3314059 nodes (2830629, 0.854128) 66.653 seconds (49721.1 NPS) 171058 nullmove try 66872 nullmove succeed (%39.0932) So you can see, not only has the PV in the last two iterations changed drastically, the node count has also increased by a factor of 2 or more! Clearly, this has to be a bug? From the opening with lazy eval off: 6 0 50 24360 1. d4 d5 2. Bf4 Bf5 3. Nf3 Nc6 7 10 263 107854 1. d4 d5 2. Bf4 Nc6 3. Nf3 Bf5 move d4 278745 nodes (225693, 0.809676) 6.184 seconds (45075.2 NPS) 5307 nullmove try 2870 nullmove succeed (%54.0795) With it on: 6 0 48 24099 1. d4 d5 2. Bf4 Bf5 3. Nf3 Nc6 7 10 257 110823 1. d4 d5 2. Bf4 Nc6 3. Nf3 Bf5 move d4 348815 nodes (289003, 0.828528) 6.985 seconds (49937.7 NPS) 9995 nullmove try 3934 nullmove succeed (%39.3597) So, I am still getting a node increase here, but the PV has remained the same. What gives!?
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