[Retros] Favour/En Passant

Kevin Begley kevinjbegley at gmail.com
Mon Jun 16 19:33:55 EDT 2014

```You keep threatening to "write much more" about many more things... When
will you ever actually address the fact that your sailboat has a hole (by
which, I mean, of course, that you have yet to produce anything resembling
a sailboat)?

On Mon, Jun 16, 2014 at 4:45 AM, Guus Rol <grol33 at gmail.com> wrote:

> Hi Kevin, Andrew and Jonathan,
>
> Actually I fully agree that pRA is the default assumption and resolves the
> issue.
>
> In fact, this is so obvious that I haven't even considered this to be
> Jonathans case. The logics are by nature a dimension separate from the
> basic conventions in the sense that they can be an independent part of the
> stipulation. In the old days I needed to write "pRA" if I didn't like the
> idea of my problem being resolved by RS. Today I need to do the reverse,
> namely add "RS".if such is what I desire. I have taken Jonathans example as
> one to be resolved under the "RS stipulation" and I answered it in this
> fashion.
>
> You can take that as a general context for my theory. Most interesting
> situations arise in RS and AP logics. In the pRA and retro-vairant logics
> all retro-active issues are compressed at the entrance gate. Though they
> are not at all obvious - especially in fairy forms - it is clear that all
> is plain sailing after the initial conditions have been established.
>
> Andrew and I will continue to diagree on the nature of conventions. I have
> written 1 post about that and will write 1 more to address the precise
> delineation (as I see it). Everyone can decide for himself which side he is
> on.
>
> Note: An essential characteristic of RS-logic is that things are different
> in the solver domain than in the player domain. You may be able to prove
> that you can mate in 1, but not be able to execute it under RS logic. See
> my PB R309. One can prove that white can mate in either 5 moves or 8 moves
> (in pRA style), but under RS logics it can only be done in 7 moves. The
> reason is that RS-logic fuses variants from different proof games. But I
> will write much more about that
>
> Best wishes, Guus Rol.
>
>
> On Mon, Jun 16, 2014 at 12:58 PM, Andrew Buchanan <andrew at anselan.com>
> wrote:
>
>>  Guus,
>>
>>
>>
>> I disagree again with your main point.
>>
>>
>>
>> First, I do agree that Jonathan’s diagram is an excellent case. But I
>> think it’s handled adequately by the existing conventions. It is not an
>> issue nor a joke.
>>
>>
>>
>> Before the recent changes to the conventions driven through by Werner
>> Keym, under the en passant convention the diagram would have no *permitted*
>> mating move. That’s fine. The sky doesn’t fall apart. Even if there was no
>> other legal move for White, this doesn’t put White in stalemate. Stalemate
>> is the result of having no legal moves. It is **not** the result of
>> having no permitted moves.
>>
>>
>>
>> It’s not a crisis: the sky doesn’t fall. We just admit the fact that in a
>> few diagrams, it is not possible to determine whether certain en passants
>> are allowable, and indeed whether the game is over or not. Those are
>> interesting diagrams, and it’s certainly not worth twisting everything in
>> order to ensure that some en passant must be allowed. That would be
>> horrible.
>>
>>
>>
>> Under the PRA convention, which now applies by default, things are even
>> more straightforward. The problem splits into two parts, according to
>> possible histories. Each history allows one en passant, so the problem is
>> solved. I believe that Werner Keym would say that the problem has 1
>> solution, in two parts. I don’t particularly like PRA in this context,
>> because it excludes any history in which neither e.p. is allowed. That just
>> makes things too easy: most of Jonathan’s work is about showing that
>> Black’s last move must have been one of the double hops. This is rendered
>> irrelevant by PRA. However, PRA is not the main point.
>>
>>
>>
>> I think our main disagreement is coming clearer. Once again you are
>> mixing together rules and conventions. My position remains that just
>> because the conventions don’t **permit** us to play a certain move
>> should have no impact at the level of the rules themselves.
>>
>>
>>
>> I made the next point in an earlier email, but I don’t think I got it
>> across to everyone so I will say it again.
>>
>>
>>
>> If rules and conventions operate at the same level as you propose, then *
>> *every** help pat is unsound, because the players are constrained by
>> convention (i.e.: the definition of mandated player behaviour in a help
>> pat) to work with one another to reach stalemate. Alternate lines of play
>> which do not end in a stalemate are irrelevant, because the players are not
>> permitted to play moves that diverge from the solution. So A1.3 kicks in
>> right at the start. Similarly, **every** direct pat is unsound. White is
>> bound by convention to eschew any path that can avoid a stalemate, and
>> despite Black’s best efforts, the composition must end in a pat. Hence A1.3
>> will kill the solution right from the start.
>>
>>
>>
>> Now the issue here, I submit, is not A1.3, but the mixing together of
>> rules and conventions. Please let’s distinguish the rules from the
>> conventions, and say the rules are about legality, while the conventions
>> constrain which legal and possibly-legal moves are permitted, then we do
>> not get in the horrible confused state that you are proposing.
>>
>>
>>
>> And I don’t even believe that your planned path makes it easier to scale
>> to fairy compositions. I think the idea of rules (including fairy rules)
>> addressing legality, and conventions (including perhaps fairy conventions)
>> then determining permissibility, is a bedrock upon which we can build a
>> solid artifice.
>>
>>
>>
>> Thanks,
>> Andrew.
>>
>>
>>
>> *From:* Retros [mailto:retros-bounces at janko.at] *On Behalf Of *Guus Rol
>> *Sent:* 16 June 2014 17:33
>>
>> *To:* The Retrograde Analysis Mailing List
>> *Subject:* Re: [Retros] Favour/En Passant
>>
>>
>>
>> Dear Jonathan,
>>
>>
>>
>> Excellent case and a real issue. There are many similar situations,
>> particularly in fairy land like with the "fuddled men" in Turnbulls
>> infamous article. I had preseved the treatment of these cases for an
>> "advanced topics" post but I can outline it here. You could have made
>> things a little worse by making sure that white was "stalemated" apart from
>> playing the e.p. moves. Deciding that white is stalemated would be illegal
>> as there would exist no proof game leading to stalemate. Clearly some e.p.
>> move must therefore be permitted.
>>
>>
>>
>> The reduction principle on the DGCs is based on the premise that some
>> preferred option for play remains but such is not always the case. Besides
>> that, there is the possibility of a "group right", a right that cannot be
>> proved for each individual member of the group but van be proved to exist
>> somewhere in the group. The handling of the cases occurs on a higher level
>> than the handling of the DGC-set / Game set.
>>
>>
>> *The natural approach is the temporary promotion of all "secondary
>> you know what I mean)  in a "rights group" allowing each one the be
>> executed as such - i.e. as if it were a right to castle. After this
>> promotion, the reduction from DGC to Game resumes with the modified
>> "rights".*
>>
>>
>>
>> One issue remains and is reflected by your example. Do you wish to allow
>> "promotion" only when no other playing option remains or do you wish to
>> allow it whenever a group right exists  - as in your example? There is an
>> aspect of personal taste in this choice, but also one of best workability.
>> Having contemplated this for a while on the basis of fairy forms, my gut
>> feeling is that it is best to stick with the first choice. Which means that
>> white cannot play e.p. in the example you presented.but he could if he were
>> stalemated (or mated) otherwise. But you are entitled to disagree since the
>> choice steps outside the necessities of a a sound and consistent
>> decisioning system.
>>
>>
>>
>> Note: On top of the retro-decisionig-tree is the 1st command: *There
>> must always be a proof game*.
>>
>>
>>
>> Best wishes, Guus Rol.
>>
>>
>>
>>
>> On Mon, Jun 16, 2014 at 10:22 AM, A J Mestel <ajm8 at maths.cam.ac.uk>
>> wrote:
>>
>> 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.
>>
>>
>> _______________________________________________
>> Retros mailing list
>> Retros at janko.at
>> http://www.pairlist.net/mailman/listinfo/retros
>>
>>
>>
>>
>> _______________________________________________
>> Retros mailing list
>> Retros at janko.at
>> http://www.pairlist.net/mailman/listinfo/retros
>>
>>
>
> _______________________________________________
> Retros mailing list
> Retros at janko.at
> http://www.pairlist.net/mailman/listinfo/retros
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://one.pairlist.net/pipermail/retros/attachments/20140616/e72ee578/attachment.html>
```