[Retros] Hit team response

Noam D. Elkies elkies at math.harvard.edu
Sun Sep 3 11:47:25 EDT 2017

andrew buchanan <andrew at anselan.com> wrote:

> Responses to emails from Noam Elkies, Nicolas Dupont & Francois Labelle.
> (1) Noam wrote:
> >https://www.janko.at/Retros/d.php?ff=2r2n2/2p1pr2/3pbkpn/5pb1/1p6/8/PQPPPPNP/RNBQKBNR
> >SPG-16.5
> >Andrew -- does this accomplish the task you had in mind?
> No - this is still the "armchair team" theme, which has been explored
> before, where *all* remaining members of the winning side are on their
> starting squares. I'm not really interested in this right now,
> because it's been worked already, while this hit team problem is new.
> This is not the subject of this thread.

OK, never mind then (for this purpose -- I still wonder if that pure
"armchair team" mate with six self-blocks might be of interest).

> It would be really great to have the composer's perspective from
> Yaakov Mintz. And Noam's Nf3# compositions too! :-)

None of the double-check mates with Nd2-f3# can be pure.
Possibly it feels like they ought to count (if there's no other
impurity than the double attack on d2), because there's no way to
"purify" it other than making the other checking piece a Bd2, which is
blatantly illegal.  But that's a discussion for some other time.

There is of course one other way that Nf3 or Nf6 can be double check
against a King on its home square.  I had a surprisingly hard time
showing this in "hit team" form; the first sound example I could find
took Popeye 3.41 almost 25 minutes to solve:

  SPG 8.5 (C+)

so it might make for a good challenge for some human solvers; solution
below after about 20 lines of blank "spoiler space".  Possibly this mate
has already been shown in a "hit team" proof-game.


1 Nf3 e5  2 Nxe5 Qf6  3 Nxd7 Qxb2  4 Nc5 Qxc1  5 Ne4 Qxb1
6 Qc1 Qxa2 7 Qa3 Qd5  8 Qe3 Qd8  9 Nf6#

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