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MatPlus.Net Forum Helpmates When castling must be the first move
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(21) Posted by Olaf Jenkner [Saturday, Jun 29, 2019 22:42]

Mirko Degenkolbe & Steven B. Dowd, 2010
(= 11+11 )

(Read Only)pid=17528
(22) Posted by Rewan Demontay (Real Name: James Malcom) [Saturday, Jun 29, 2019 23:46]

Thanks for that view Olaf!
(Read Only)pid=17529
(23) Posted by Rewan Demontay (Real Name: James Malcom) [Friday, Jul 19, 2019 23:34]; edited by Rewan Demontay (Real Name: James Malcom) [19-07-19]

I do note that the 8.5 is the record for which the ENDING move. But that sort of thing kind of HAS to be dual-free, so I'm not meddling with that.

Frank's h#7 is the record for a dual-free problem with castling as the first move.

It is possible to extend Frank's setup with this dual-heavy setup.

BTM, h#10

(= 9+9 )

This allows for a h#10. Feel free to find the solution, as I am not giving it away. It took me quite some time to find it myself.

Assuming that we always a WP on the g-file (to "lock in" the rook) blocked by a BP, I think that's it's impossible to achieve a h#11.

A WP g6 allows for a h#9 with a promotion

A WP g5, if you try promotion, there is a #11, but the #10 still exists, beating the 11.

A WP on g4 is the same story and g3 and g2 obviously don't work.

If you place the WP legally, it must be protected by other pawns and blocked in order to achieve a long mate.

If you try a WP f3, the only possible protected square, it ties for #10 with promotion involved.

But since that ties for the #11 without be those pawns, the f3 try can be killed off by the convention of trying to be economic.

So, all in all, as far as I can tell, my diagram for extending Frank's idea, with duals allowed, may be the best possible.

I even pulled up the e-file pawns up a step (from White's view) for fun, and I still found a h#10. A WP to fill in the e3 gap doesn't make a difference.

So I suppose that my diagram is the best of these two h#10 is the sense that it is much tougher to solve.

Can anyone can make good use of the now two
usable pawns with potential, one of each color, in my diagram?
(Read Only)pid=17602
(24) Posted by Eric Huber [Friday, Jul 19, 2019 23:50]

I am not sure what can be done with the two additional pawns, but in this setting the helpmate in 10 is cooked in 7 moves.
For instance: 1.Bd1 Ra2 2.bxa2 b3 3.cxb3 c4 4.b2 c5 5.b1=R c6 6.Rb7 c7 7.Ra7 c8=Q#

There are also innumerable cooks in 8, 9 and 10 moves.
1.Ka7 Ra2 2.bxa2 b4 3.Kb6 b5 4.Kc5 b6 5.a1=B b7 6.Bxc3 b8=Q 7.Bd4 exd4+ 8.Kxd4 Qd6#
1.Ka7 Ra2 2.bxa2 b4 3.a1=B b5 4.Bxc3 b6+ 5.Ka6 b7 6.Bb4 b8=Q 7.Ka5 Qb7 8.Bd1/Bf1 axb4#
(Read Only)pid=17603
(25) Posted by Rewan Demontay (Real Name: James Malcom) [Saturday, Jul 20, 2019 00:30]; edited by Rewan Demontay (Real Name: James Malcom) [19-07-20]

Eric, it is not cooked because it is White who mates, not Black. Sorry for not mentioning that!

EDIT: Nevermind! Sorry once more!

Man, it sucks that my diagram is cooked. The mating square that I originally had in mind for the BK was f3.

Additionally, any solution in 10 is not considered a cook, as per this one diagram, to me since I specifically mentioned that the point was to allow duals.
(Read Only)pid=17604
(26) Posted by udo [Monday, Sep 21, 2020 08:41]

(= 12+9 )

U. Degener/M. Degenkolbe
The Problemist, 2020
h#10 (12+9)

1.Bg2 Bc1 2.Bf1 Bb2 3.Be2 Bc1 4.Bd1 Bb2
5.Bc2 Bc1 6.B×b1 Bb2 7.B×a2 0-0-0 8.B×c4 Rh1
9.B×d5 c4 10.Bf7 Rh8

length-record for h# with castling
(Read Only)pid=19665
(27) Posted by Rewan Demontay (Real Name: James Malcom) [Tuesday, Sep 22, 2020 05:01]

Thanks for the great news, udo! However, may you please also post it in this more relevant thread?:
(Read Only)pid=19667
(28) Posted by udo [Wednesday, Sep 23, 2020 10:38]

(= 7+9 )

U. Degener/M. Degenkolbe
10° Maroc Echecs, 2020
4° Recommande
h#8 (7+9)

1. e5 0-0-0 2. e4 Rd3 3. ed3 e4 4. de2 e5 5. e1B e6 6. Ba5 e7 7. Bd8 ed8S 8. a5 Sf7#

h#8 with castling at the first move

"This problem certainly doesn't bring anything new..." (judge)
(Read Only)pid=19672

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MatPlus.Net Forum Helpmates When castling must be the first move