[Retros] rstan

Andrew Buchanan andrew at anselan.com
Sat Oct 5 10:40:23 EDT 2013

Hi François,

Thanks for the verification - I am glad the latest is sound - I think it's
the most fun of the ones I've sent, as well as being the shortest.

I do have a shorter one, but the minimal solution is missing a capture that
the longer solutions include. I suppose therefore it shouldn't count.

If any more of these are produced, I hope it's not too late to ditch the
inappropriate & misleading name. These are nothing to do with proof games. I
would use the term "half synthetic". They have the feel of kriegspiel, too.

On disambiguation, I think option c is the most natural & the best:
"A fractional synthetic is obtained by taking the solution as written in
algebraic notation and blanking the hidden plies."


-----Original Message-----
From: retros-bounces at janko.at [mailto:retros-bounces at janko.at] On Behalf Of
Francois Labelle
Sent: 05 October 2013 02:47
To: retros at janko.at
Subject: Re: [Retros] rstan

On 10/02/2013 09:14 PM, Andrew Buchanan wrote:

> Shorter again:


> 1. d4 ... 2. dxe5 ... 3. Qxd7+ ... 4. Qd6+ ... 5. Qd7+ ...

> then:

> 1004. Qc6 ... 1005. Qc4 ...#

C+ again. Here's the solution with 2.0 moves added to the shortest line:
1. d4 e5 2. dxe5 Ba3 3. Qxd7+ Kf8 4. Qd6+ Ke8 5. Qd7+ Kf8 6. Qc6 Qg5 7.
Qc4 Qxc1#

On 10/02/2013 08:53 PM, Richard Stanley wrote:


> One could also look at "half proof games" with various conditions. For

> instance, does there exist such a game that ends in mate by a pawn

> promoting to a knight? The moves of the side being mated are specified.

Interesting. We don't know the full potential of "half proof games" yet, but
right now I worry that the genre isn't well-defined. The problem is what to
do with the disambiguating moves in algebraic notation.

Take for example the white moves
1. Nf3 ... 2. Nd4 ... 3. Na3 ... 4. Ndb5 ...

We could take any of the following viewpoints:

a) Half proof games never use disambiguation. In the example we would write
"4. Nb5" and determining which knight moved would be part of the problem.

b) Half proof games always use disambiguation. In the example we would write
"4. Ndb5" even if Black captured Na3 in move 3, so as not to give
information about whether Na3 was captured or not. In other words, all the
white moves are crystal clear as if we used long-hand notation everywhere
(1. Ng1-f3 ... 2. Nf3-d4 ... 3. Nb1-a3 ... 4. Nd4-b5 ...).

c) Half proof games use disambiguation according to algebraic notation rules
). In the example, writing "4. Ndb5" would imply that Black didn't capture
Na3, and writing "4. Nb5" would imply that Black captured either
Na3 or Nd4. In other words, a half proof game is obtained by taking the
solution as written in algebraic notation and blanking the hidden plies.

I wonder which viewpoint people think is best. So far the problems people
have posted aren't affected by this, but if the genre takes off, someone is
going to test those boundaries someday...


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