[Retros] Hit Team theme progress

Noam D. Elkies elkies at math.harvard.edu
Wed Aug 30 16:20:15 EDT 2017

andrew buchanan <andrew at anselan.com> writes:

> Sorry to not be in touch for a couple of days,
> but I was stuck in another part of the forest.


> Two things are being confused, which sort of intersect in
> THC mate. Let me explain.

> (1) What I was proposing here with "Hit Team" is the idea that all surviving units from both sides are homebase, *except* for the mating units. 

> (2) Noam I think was remembering an earlier activity in this mailing list,
> whereby all the mating side were homebase but the mated side were free to
> roam where they wanted. My file for these looks like this:
> 001 rnbqkbnr/ppppppp1/8/8/4P3/3B4/PPPPNPP1/RNB3RK w - - id PG 7.0 [...]
> [...] 005 rnb3rk/ppp2pp1/2qb4/4p3/8/8/PPPPPPP1/RNBQKBNR w - - id PG 8.5
> published retro mailing list - version Noam Elkies; [...]

Is the last of these the correct position?  As it stands it's not mate
(9 . . . Bh3).

> (3) Now obviously if you combine these two, then you get total homebase,
> but no mate is possible here, but I was wondering one might then relax
> the THB condition and have THC. weP & weP promoted to Q/R, wdP vanishes,
> together with bdP, beP, bfP bQ, bBs, bkN.

White e and f pawns, I suppose -- not e and e pawns.

>  But that seems too much of an ask, so that was what I'd reported
> I'd given up on. Sorry for confusion.

Yes, that does seem rather too ambitious to hope for...

> (4) Now Noam has just sent an email with a very interesting THC position
> - he is basically taking the Eight Officers idea and allowing for
> pawns to promote and return.

That's what Juha was suggesting with the example that ended
14 Ng2+ Kh3 15 Ng1#.  (What's the source of that proof game?)
Getting a pure mate under this restriction seemed challenging but
not hopeless.  I don't know now whether it's sensible to wonder
whether my realization is the first one, whether deliberately
or by happenstance.


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