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MatPlus.Net Forum General News from Jacobi
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(1) Posted by [Saturday, Oct 5, 2019 14:19]; edited by [19-10-05]

News from Jacobi

Jacobi is an extremely valuable program to solve fairy chess proof game problems, realized by the Canadian specialist Francois Labelle. It can also solve some ordinary help stipulations. The last implemented conditions are Cage Circe and Anti Cage Circe. The first one is an invention by Nicolas Dupont from 2009. The second is a natural combination between Cage Circe and Anti Circe. The simplest definition is: AntiCirce in which the rebirth square is a cage. But the definition must be detailed. I assume that:
Anti Cage Circe (type Calvet)
1.On making a capture, the capturing unit (including King) is reborn as in a Cage Circe rebirth(*). The captured unit disappears, as in normal chess.
2.When there are more than one cage, the side making the capture chooses the rebirth square from the available cages.
3.Since rebirth is obligatory, a capture is legal only if the capturing unit may find a rebirth cage.
4.It is possible to answer a check by spoiling the cage where the checking piece would be replaced.
5.Promotion with capture is legal provided the promoted unit may find a rebirth cage.
6.White pawns may be reborn on the 1st row, from which they can move like ordinary pawns, including making a double step from the second row. Same for black pawns.
7.White pawns may also be reborn as promoted pieces on the last row. In such case, the rebirth square must be a cage for the promoted piece, the type of which is chosen by the side making the capture. Same for black pawns.
8.A King may capture only if he can find a rebirth cage and not end in check; however, he may threaten to capture the opposing King even if after rebirth he would be in check.
9.Captures, in which the capturing piece lands on a cage square, are allowed.
10.A replaced Rook, King (or Rook and King) may be used for castling, provided the usual castling rules are satisfied.

(*)Rebirth squares are called cages. A cage for a given piece is a square such that if the given piece lied on that square, its only legal moves would be captures.

This is the standard type. If rule 9 is denied (captures in which the capturing piece lands on a cage square are not allowed) then we have Anti Cage Circe type Cheylan.
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(2) Posted by Joost de Heer [Saturday, Oct 5, 2019 15:04]


9.Captures, in which the capturing piece lands on a cage square, are allowed.

In type Cheylan, is the capture allowed if there are multiple cages and the rebirth is in a different cage?
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(3) Posted by [Saturday, Oct 5, 2019 17:24]

Good question. I'm tempted to answer "yes". If the captured piece is in a cage and the capturing piece lands in another cage, then we have also type Cheylan.
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(4) Posted by François Labelle [Sunday, Oct 6, 2019 01:59]

The mechanics of AntiCageCirce Cheylan should be similar to AntiSuperCirce Cheylan.
To clarify rule 9, it could be rewritten to be about cages and not about captures:

9. A cage which coincides with the square of capture is allowed.

Cheylan would be the opposite: A cage which coincides with the square of capture is not allowed.
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(5) Posted by [Sunday, Oct 6, 2019 08:09]

Agreed with Labelle's suggestion. This work is rather demonstrative:

P. Raican
(= 13+13 )
Anti Cage Circe
PG 9
Sol: 1.h4 Sf6 2.Rh3 Se4 3.Rg3 Sxd2 [bSd2->h1] 4.Bg5 Sc6 5.f4 Sd4 6.Kf2 Sxe2 [bSe2->h3] 7.gxh3 [wPh3->g8=B]! f5 8.Bxh7 [wBh7->h6] Kf7 9.Qxd7 [wQd7->h7] gxh6 [bPh6->g7]

B Ceriani-Frolkin. It is paradoxical, but h7 is a cage for wQ, Qh7-g8 or Qh7-g6 are selfchecks. Partially checked by Jacobi.
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MatPlus.Net Forum General News from Jacobi