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Subject: Re: perpetual check (or not!)

Author: Robert Hyatt

Date: 07:04:29 03/19/00

Go up one level in this thread


On March 19, 2000 at 09:22:02, Frank Schneider wrote:

>Hi all,
>
>here are two testpositions, one where there is a perpetual check (1. Rg5+) and
>one, slighlty modified, where the perpetual check is no longer possible.
>Which program sees a draw in the first position but not in the 2nd?
>
>Frank
>
>
>Pos 1:
>[D]r7/8/4p3/5b1k/3p3r/Np6/1P4R1/K5R1 w - -
>
>Rg5+ draws by perpetual check (or stalemate)


               10->   6.46  -4.23   1. Rd2 d3 2. Kb1 e5 3. Nb5 Bg6 4. Rc1
                                    Ra5 5. Nd6 Ra2
               11     9.87  -4.36   1. Rd2 d3 2. Kb1 Rc8 3. Rf1 Kg5 4.
                                    Rg2+ Kf6 5. Rd2 Ke5 6. Nb5 Rhc4
               11->  12.66  -4.36   1. Rd2 d3 2. Kb1 Rc8 3. Rf1 Kg5 4.
                                    Rg2+ Kf6 5. Rd2 Ke5 6. Nb5 Rhc4
               12    15.97  -4.37   1. Rd2 d3 2. Kb1 Rc8 3. Rf1 Kg5 4.
                                    Rg2+ Rg4 5. Rd2 Rf4 6. Rh1 Be4 7. Rc1
               12    16.92     ++   1. Rg5+!!
               12    16.95   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               12->  17.01   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               13    17.16   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               13->  17.23   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               14    17.35   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               14->  17.43   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               15    17.68   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               15->  17.83   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               16    18.33   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               16->  18.61   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               17    19.64   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5
               17->  20.18   0.00   1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kxg5




>
>Pos 2:
>[D]r7/8/8/4p2k/3pb2r/Np6/1P4R1/K5R1 w - -
>
>now there is no longer a perpetual check after Rg5+, e.g.:
>
>1. Rg5+ Kh6 2. Rh5+ Kxh5 3. Rg5+ Kh6 4. Rh5+ Kg7 5. Rg5+ Kf7 6. Rg7+ Ke8 7.
>Re7+ Kd8 8. Rd7+ Kc8 9. Rc7+ Kb8 10. Rc8+ Ka7 11. Rc7+ Bb7


               11->  15.18  -2.94   1. Rg5+ Kh6 2. Rxe5 d3 3. Re6+ Kh7
                                    4. Re7+ Kh8 5. Rf1 Rc8 6. Rd7 Rh2 7.
                                    Re1 d2 8. Rxd2 Rxd2 9. Rxe4
               12    30.68  -3.11   1. Rg5+ Kh6 2. Rxe5 d3 3. Re6+ Kh7
                                    4. Re7+ Kh8 5. Rd7 Rh2 6. Re7 Re2 7.
                                    Rd1 Bc6 8. Rf7 Kg8
               12->  31.63  -3.11   1. Rg5+ Kh6 2. Rxe5 d3 3. Re6+ Kh7
                                    4. Re7+ Kh8 5. Rd7 Rh2 6. Re7 Re2 7.
                                    Rd1 Bc6 8. Rf7 Kg8
               13     1:03  -3.18   1. Rg5+ Kh6 2. Rxe5 d3 3. Re6+ Kh7
                                    4. Rd6 Rh2 5. Rd4 Re2 6. Rd1 Bg6 7.
                                    Rd7+ Kh6 8. R7xd3 Bxd3 9. Rxd3
               13->   1:05  -3.18   1. Rg5+ Kh6 2. Rxe5 d3 3. Re6+ Kh7
                                    4. Rd6 Rh2 5. Rd4 Re2 6. Rd1 Bg6 7.
                                    Rd7+ Kh6 8. R7xd3 Bxd3 9. Rxd3
               14     1:56  -3.28   1. Rg5+ Kh6 2. Rxe5 d3 3. Re6+ Kh7
                                    4. Rd6 Rh2 5. Rd4 Bg6 6. Rd6 d2 7.
                                    Rdxg6 d1=Q+ 8. Rxd1 Kxg6 9. Rf1 Rd2
                                    10. Kb1 Rc8
               14->   2:02  -3.28   1. Rg5+ Kh6 2. Rxe5 d3 3. Re6+ Kh7
                                    4. Rd6 Rh2 5. Rd4 Bg6 6. Rd6 d2 7.
                                    Rdxg6 d1=Q+ 8. Rxd1 Kxg6 9. Rf1 Rd2
                                    10. Kb1 Rc8


I am not sure why any program would break in either of the two positions
above...





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