[Retros] Retro composing tourney : Kamikaze and Rex Inclusive

andrew buchanan andrew at anselan.com
Sun Jul 12 06:04:20 EDT 2020

Dear retro friends,

I think a rule is missing in the Kamikaze R.I. conditions.

Die Schwalbe's Fairy Glossary states (my translation):

Kamikaze rex inclusive: A capturing unit (including the king) disappears from the board as well as the captured unit. (Therefore, kings are not allowed to capture unless there are further [fairy] conditions [e.g. Circe].)(The original is:
Die Schwalbe Märchenschachlexikon:
"Kamikaze rex inclusiv: Der schlagende Stein (einschließlich König) verschwindet beim Schlagen selbst mit vom Brett. (Ohne weitere Bedingung dürfen Könige daher nicht schlagen.)")
I am unconvinced about the "therefore/daher". There is no orthodox rule that implies you can't explode your own king: we need to specify it.

Basically, Kamikaze R.I. is exactly Atomic Chess with only "tactical nukes" - when a capture happens the neighbours aren't touched. (See: https://en.wikipedia.org/wiki/Atomic_chess.) Atomic Chess necessarily has a specific rule "Captures that result in the explosion of a player's own king are illegal, and therefore a king can never capture any other piece." We need exactly such a rule in Kamikaze R.I.

Because exploding one's own king is illegal, a player can be stalemated if not in check, if the only legal move would otherwise be to capture an undefended enemy unit.

And hence in both games: because the king cannot take another piece, it is possible to move the kings next to each other without a check occurring.


    On Sunday, July 12, 2020, 12:16:32 AM GMT+8, Alain BROBECKER via Retros <retros at janko.at> wrote:  
 Pascal Wassong asked:
>P0007627 by Günter Lauinger has solution Ng5-h7, but if kings
>can be in contact, the last white move could have been Kf7-g8,
>so there are several last moves possible.
>The stipulation of this problem is Rex Inclusiv.
The question/remark was also asked by other people.
Maybe in this two problems, Günter Lauinger, unlike what
is stipulated in the current tourney, didn't consider that
Kings can go one near the other?
(In this time of social distancing it sure can be surprising)

Also, if at one point you want the king to go one near the other,
not many programs allow to do that, but at least iNatch 0.6.2 by
Pascal Wassong in edit mode allows to place Kings nearby.

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