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| | | (1) Posted by Hauke Reddmann [Tuesday, Feb 17, 2015 16:58] | On a retro theme
Im not THAT interested in retro, but just curious:
It's a not uncommon feature in a SPG that pawns captured
overcross: axb, bxa.
Do you have examples for wi(l)der permutations, eg. the
a- and c-pawn swapped lines, or a->b,b->c,c->a?
Hey, would it be thinkable to have the a-pawn queen on g8
and the g on a8? :-)
Hauke
| | | (2) Posted by Joost de Heer [Wednesday, Feb 18, 2015 20:13]; edited by Joost de Heer [15-02-18] |
On PDB:
P1004050 (exc and cxe)
P1000474 (bxg and gxb)
P1004037 (dxe, exf, fxd)
P1004018 (dxf, exd, fxe)
| | | (3) Posted by Hauke Reddmann [Thursday, Feb 19, 2015 17:17]; edited by Hauke Reddmann [15-02-19] |
Wow. Explanation why for retro dummies? :-) (For P1000474)
| | | (4) Posted by Joost de Heer [Thursday, Feb 19, 2015 17:39] |
The 'why' in SPGs is always easy: because it's the only way to reach the position in the given number of moves :).
| | | (5) Posted by Geoff Foster [Friday, Feb 20, 2015 03:05] |
Andrei Frolkin & Mikhail Kozulya
(dedicated to T. Volet)
2 Prize, StrateGems 2000 (= 15+6 )
PG 17.5
1.e3 h5 2.Qg4 hxg4 3.Se2 Rh3 4.Rg1 Rf3 5.gxf3 e5 6.Bg2 e4 7.fxe4 d5 8.exd5 Sc6 9.dxc6 Bb4 10.cxb7 Bc3 11.bxc3 Qd4 12.cxd4 Bf5 13.Sbc3 Kd7 14.Rb1 Re8 15.Rb2 Re5 16.dxe5 Sf6 17.exf6 Bh7 18.fxg7
Assume that the wPb7 and wPg7 are on their original files. How were the black d-file and e-file Pawns captured? They cannot have been captured by the same wP (because of the above assumption). If the wQ captured one of them then the wQ made at least 2 moves. The white rooks, bishops, knights and wPe3 made 7 moves, so this leaves just 9 moves for the wPb7 and wPg7. To do this one of them must have started with a double-step move, so it can only have made 2 captures. In addition, the other wP (which made 5 moves) can only have made 4 captures.
I was hoping to show that this is impossible, but I'm having trouble. It just happens that the wPs cannot afford to waste 3 moves on non-captures. With the wPb7 and wPg7 swapping files, they can make the required 10 captures on their own. The black d- and e-file pawns can easily be sacrificed, and this opens up the centre for further black moves.
| | | (6) Posted by Dupont Nicolas [Friday, Feb 20, 2015 14:09] |
Crossed captures may also be used to make invisible Ceriani-Frolkin pieces (= captured promoted piece).
Nicolas Dupont & Silvio Baier
15864 Die Schwalbe 265 (2014)
 (= 12+14 )
PG 30.0 C+
1. Ph2-h4 Pa7-a5 2. Ph4-h5 Pa5-a4 3. Ph5-h6 Pa4-a3 4. Ph6xg7 Ph7-h5 5. Pf2-f4 Ph5-h4 6. Pf4-f5 Ph4-h3 7. Pf5-f6 Ph3-h2 8. Pf6xe7 Pf7-f5 9. Pb2-b4 Cg8-f6 10. Pg7-g8=D Pf5-f4 11. Dg8-b3 Ff8-h6 12. Db3-b2 Pa3xb2 13. Pg2-g4 Ta8-a3 14. Pg4-g5 Ta3-g3 15. Pg5-g6 Pf4-f3 16. Pg6-g7 Fh6-f4 17. Pg7-g8=F Th8-h6 18. Fg8-c4 Pd7-d5 19. Pb4-b5 Re8-d7 20. Pe7-e8=T Pd5xc4 21. Te8-e6 Cf6-d5 22. Te6-a6 Pb7xa6 23. Pb5-b6 Rd7-c6 24. Pb6-b7 Rc6-b6 25. Pe2-e4 Rb6-a7 26. Pe4-e5 Cd5-b6 27. Pe5-e6 Dd8-d3 28. Pe6-e7 Fc8-e6 29. Pe7-e8=C Fe6-d5 30. Ce8-d6 Pc7xd6
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