[Retros] No occupied white square

[Olli Heimo]

Unto Heinonen wants this to be published on the mailing list as a New Years Greeting: r1b1k1n1/1p1p1p1R/r1p5/3p3p/P7/3K1N1P/q1P1P1P1/1N1Q1B1R (12+12). Proofgame in 13.0 moves. This is because he informed me that he has now a sound proof game in 15,5 moves leaving 25 men on same-coloured squares and he is working with 26 men. Happy New Year, Olli.  
Francois Labelle kirjoitti 24.12.2013 kello 22:12:

> On 12/20/2013 10:39 AM, Olli Heimo wrote:

> > Unto Heinonen was really surpised when he heard that Francois had done

> the task in 10.0 moves. We are eager to see the positions.

> 

> The two positions will be published in Phénix (2014).

> 

> > Meanwhile Unto has thought the theme otherwise. Maximize the number of

> men left on the board in a sound proofgame ending to the position

>  where all

> men are on same-coloured squares. Unto has one with 24 men left in 13.0

> moves.

> 

> Nice. The best I have so far is 23 men in 10.5 moves. Here's the 

> frequency distribution in 10.5 moves:

> 

> #men, #unique proof games

> 17 11

> 18 35

> 19 85

> 20 64

> 21 61

> 22 18

> 23 1

> 

> >   He will publish it in February-2014 in Tehtäväniekka, unless before

> that someone breaks his record.

> 

> I started a search in 11.0 moves limited to 25+ men to speed it up, but 

> progress is very slow. I'll keep you informed.

> 

> Before that I did a special search for a proof game in 11.0 moves with 

> exactly 24 men and ranks 4 and 5 empty. I didn't find anything, but

>  here 

> are two close calls:

> 

> 1. e3 d6 2. Bc4 Qd7 3. Bxf7+ Kd8 4. Bd5 b6 5. Bxa8 Bb7 6. g3 Bxh1 7. 

> Bxh1 Nf6 8. Bc6 Qxc6 9. a3 Qxc2 10. Nc3 Qxc1 11. Qxc1 h6

> 

> 1. d3 h6 2. Bxh6 g6 3. Bxf8 e6 4. Bc5 c6 5. Bxa7 Qb6 6. f3 Qxg1 7. Bd4 

> Qxd4 8. b3 Qxa1 9. h3 Qxb1 10. Qxb1 Na6 11. Kd1 Rh7

> 

> Each only have a slight dual

> 7... h6  11... Nf6

> 

> 10... Rh7 11... Na6

> 

> This should give you guys something to chew on while you wait for the 

> sound proof games...

> 

>      François

> 

> > Noam Elkies kirjoitti 06.12.2013 kello 19:28:

> >> Francois Labelle <flab at wismuth.com> writes:

> >>

> >>> My computer found a unique proof game in 10.0 moves with 21 men all on

> >>> white squares, and another unique proof game in 10.0 moves with 21 men

> >>> all on black squares. A lovely pair of problems! Both are confirmed by

> >>> Euclide.

> >>>

> >>> Looks like this is computer territory. Sorry Unto!

> >>>

> >>> Now I'd like to know if Unto is still going to publish his 11.0-move

> >>> problem in a magazine, and whether I should publish my 2 problems in a

> >>> magazine...

> >> I don't see why not.  Heinonen's problem was still the first of its kind

> >> (albeit by only a few days thanks to near-instantaneous global

> >> communication);

> >> and the mechanism is probably different.  And you've already

> >>   published some

> >> of your earlier computer discoveries in problem magazines, so why

> >>   not these?

> >>

> >> NDE

> >>

> >> P.S. Is it feasible to compute how many such proof games there are in

> >> 10.5 or even 11.0 and beyond?  It would be interesting to see what

> >> the range of possibilities is (and how much choice Heinonen had for

> >> his 11.0-mover).

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> >>

> >>

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