[Retros] rights & ocassions / not answering Andrew anymore

Andrew Buchanan andrew at anselan.com
Tue Jun 3 00:26:36 EDT 2014

Dear Guus,


I still don’t see that a rule can know that a convention will trigger. For example, en passant convention indicates whether a move is *permitted*, but there are no retro-analytic implications, except in the branch of moves in which the en passant is actually played. A1.3 will not be able to use the absence of proof of e.p. legality to terminate the game. 


Similarly here, with 3R convention currently a draw may be automatically asserted. But A1.3 will have no visibility that a mere convention is going to be triggered. How could it?


This distinction between rules and conventions may be different to how you’ve seen it, but it is clean and consistent. Please think about it. I am a bit troubled that you don’t get it.




From: Retros [mailto:retros-bounces at janko.at] On Behalf Of Guus Rol
Sent: 02 June 2014 21:37
To: The Retrograde Analysis Mailing List
Subject: Re: [Retros] rights & ocassions / not answering Andrew anymore


Hi Olli,


Things are not that complicated. You can always construct one proof game for the diagram in less than 41.5 moves in which Rg8+ draws because of 3R occurring at the next move Bf8. This is sufficient to dual the intended solution. Of course, still on the premise that 3R is automatic by convention.


Best wishes, Guus.

On Wed, May 28, 2014 at 4:16 PM, Olli Heimo <olli.heimo at luukku.com> wrote:

Hi Joost-
I can't decide if I agree or disagree. The Codex says: "Article 18 - Repetition of Position
A position is considered as a draw if it can be proved that an identical position [21] has occured three times in the proof game combined with the solution". So after the forced 32. - Bf8 the game is over and neither player can anymore checkmate. It follows that the game is over already after 32.Rg8+. But one can't prove that it is an identical position. In certain proofgames it is a fact, but if e.g. 19.Na3 Rb8 20.Nb1 Ra8 it is not identical. There are several rules competing with other rules. Which one is the strongest? Olli.

Retros Probleemblad kirjoitti 27.05.2014 kello 17:51:

> On 05/27/2014 11:57 AM, Guus Rol wrote:
> > Hi Olli,
> > Yes, you got the idea! I am not sure about the precise position and
> > timing but basically DR cooks it if you aim for the position after Bf8.
> I don't think so. DR uses article 5.1b ("The game is drawn when a
> position has arisen in which neither player can checkmate the

>  opponent?s

> king with any series of legal moves."). Since ignoring the 3-fold
> repetition is legal, there's a legal continuation in which any colour
> can checkmate.
> Joost
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> Retros at janko.at
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