[Retros] Favour/En Passant

[A J Mestel]

Now that I'm connected again, I'll repost something I wrote a month ago.
It feels a bit like a poor joke, which had some point at the time, but 
loses everything in the re-telling, but still, here it is/was.

     Jonathan

Date: Fri, 6 Jun 2014 11:04:56 +0100 (BST)
From: A J Mestel <ajm8 at maths.cam.ac.uk>
To: The Retrograde Analysis Mailing List <retros at janko.at>
Subject: Re: En passant

Did this ever get posted in the list? I never saw it, and got no replies.
It's a bit dated now, but someone said that en passant was only legal if 
you could prove what the previous move had to be etc. Needs to be a bit 
more precise.
   Jonathan

On Wed, 28 May 2014, A J Mestel wrote:

> Someone must have done this before, but consider:
>
> W: Kc5 Rd8 Bc8 Nc6 a5 a6 e5 e6
> B: Kc7 Bb8 b5 d5
>
> Can White mate in one? Not according to the definition I read here a few
> mails ago.