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MatPlus.Net Forum General Double Check Selfmates

### Double Check Selfmates

I had a funky idea today: the most double check selmates in a position. Basically, it’s a selfmate where one side forces the other side to checkmate them with a double check.

I managed to find 9. Three black knights can move to d4 to deliver check. White has only three legal responses to each black knight check-to take with one if their white knights and deliver a doublecheckmate at the same time. 3*3=9.

(= 10+7 )

Is 10 or more possible? Additionally, are there any known problem that features this theme or something similar?

I’m also curious about a problem with a string of double checks as the solution and/or strongest moves.

I did find this nice #s4 on yacpdb.

Seyferth, Paul Karl Edmund
Die Schwalbe (2951) 1934-03

(= 10+5 )

I just threw out my 9 with a damned 28!

(= 13+9 )

Each black queen and rook, all 7 of them, take the white pawn on d4. For each capture, white has only 4 legal moves, and each one results in a doublecheckmate to the black king. 7*4=28. Huzzah!

I severely doubt that this can be improved at all now. Sorry for ruining the fun!

I’ll make a proof game of legality and adjust my position if it is not legal to make it legal.

UPDATE: 1. h4 g5 2. g4 f5 3. f4 e5 4. b4 exf4 5. c4 fxg4 6. d4 gxh4 7. e4 h5 8. a4 b5 9. axb5 c5 10. bxc5 d5 11. exd5 a6

And indeed the position is legal indeed. All needed promoting pawns are now on their way to promotion, the d4 and a6 pawns are in place, and white will be able to attain two light squared bishops with the doubled c-pawns.

I assume that you don't mean BOTH sides keep doublechecking,
although this can fairily :-) easy done with lion, nighthopper
and nightrider.* (Can one do it only with grasshoppers?
You can parry a queen/grasshopper double check with a
non-king move after all!)
In the latter case, OTB game examples exist and I'm willing to bet
you find stuff on Tim Krabbes Chess Curiosities page.

(= 7+8 )

* La7,c7,NHe2,d2,Na8,b8. Draw :-)

Hauke

You’re right that I’ve seen a similar thing on Krabbe’s site before!

From Tim Krabbe #120-Here is a setup with mutual perpetual check that uses Nightriders.

(= 3+3 )

Also, Arisktotle from chess.com has achieved a new record of 32 in the domain of most selfmates via doublecheck, An extra battery, and some knights were added to my matrix for 28. It is a legal position.

https://www.chess.com/forum/view/endgames/triple-checkmate?page=3

BTM, s#1, 32 Variants

(= 16+11 )

when white double checks same it not relevant which piece is captured. so no 32

(7) Posted by Rewan Demontay (Real Name: James Malcom) [Saturday, Sep 28, 2019 00:45]; edited by Rewan Demontay (Real Name: James Malcom) [19-09-28]

Yes it does matter, seetharam.The count is for many possible variations there are, which there are 32 of. Each capture is a variation.

After some more back and forth work on the forum, Arisktotle and I have produced this jewel.

BTM, s#1 Via Double Check, 88 Variations

(= 11+14 )

MatPlus.Net Forum General Double Check Selfmates