Author: Anthony Cozzie
Date: 22:02:17 02/15/03
[D]3r2k1/pR3ppp/3Qp3/4n3/2P1PP2/4B3/4KP2/7q b - - 0 30 Zappa gives: 1...Qh5 2. Kf1 Qh1 3. Ke2 Qh5 = (9.21) Depth: 4 00:00:00.03 2kN 1...Qh5 2. Kf1 Qh1 3. Ke2 Qh5 = (9.21) Depth: 5 00:00:00.08 6kN 1...Qh5 2. Kf1 Qh1 3. Ke2 Qh5 = (9.21) Depth: 6 00:00:00.26 20kN 1...Qh5 2. Kf1 Qh1 3. Ke2 Qh5 = (9.21) Depth: 7 00:00:00.63 54kN 1...Qh5 2. Kf1 Qh1 3. Ke2 Qh5 = (9.21) Depth: 8 00:00:01.34 131kN 1...Qh5 2. Kf1 Qh1 3. Ke2 Qh5 = (9.21) Depth: 9 00:00:02.49 295kN 1...Qh5 2. Kf1 Qh1 3. Ke2 Qh5 = (9.21) Depth: 10 00:00:04.92 688kN 1...Qh5 2. Kf1 Qh1 3. Ke2 Qh5 = (9.21) Depth: 11 00:00:09.54 1542kN which is clearly silly. Without the transposition table, I get the following, rather messy, output: 1...Rb8 - (9.63) Depth: 8 00:00:10.94 1532kN 1...Qh5 2. Kf1 Qh1 3. Ke2 Qd1 4. Qxd1 Rxd1 - (8.13) Depth: 8 00:00:17.33 2434kN 1...Qf3 2. Kf1 Qh1 3. Ke2 Qh5 4. Kf1 Nc6 5. Rd7 Qh1 6. Ke2 Rxd7 7. Qxd7 Qxe4 = (3.56) Depth: 8 00:00:20.96 3011kN 1...Qf3 2. Ke1 Qh1 3. Ke2 Qh5 4. Kf1 Qh3 5. Ke2 Qg4 6. Kf1 Qxf4 - (3.06) Depth: 9 00:00:35.07 5489kN 1...Qf3 2. Ke1 Qh1 3. Ke2 Qh5 4. Kf1 Qh3 5. Ke2 Qg4 6. Kf1 Qh4 7. Qxd8 Qxd8 8. fxe5 Qd3 9. Kg2 = (2.61) Depth: 9 00:00:50.34 8168kN 1...Qh5 2. Kf1 Qh1 3. Ke2 Qf3 4. Ke1 Nc6 5. Rd7 Qh1 6. Kd2 Qh5 - (2.11) Depth: 10 00:01:31.06 15360kN 1...Qf3 2. Ke1 Qh1 3. Ke2 Qh5 4. Kf1 Qh3 5. Ke1 Nc6 6. Rd7 Qh1 7. Ke2 Rc8 8. f3 a5 = (2.40) Depth: 10 00:02:22.18 24297kN 1...Qf3 2. Ke1 Qh1 3. Ke2 Qh5 4. Kf1 Nc6 5. Rd7 Qh1 6. Ke2 Rc8 7. f3 a5 8. Bc5 Qc1 = (2.20) Depth: 11 00:04:18.74 43985kN At depth 8, it starts to realize it is running out of checks, but even at depth 11 it doesn't really understand the position. The problem appears to be as follows: Zappa analyzes the position at depth 1, and determines it can win white's queen with Rxd6. Search is stopped. Zappa analyzes the position at depth N, and follows the tree Qh5 Kf1 Qh1 Ke2. Here Zappa does not declare a repetition because the position has occurred only 1 time in the tree. However, this is the root position, and its value has been stored in the hash as 9.21 by iteration N-1. And the cycle continues. There has to be some way to fix this, but I can't seem to find it. anthony
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