Adrian Storisteanu

Original Retro & PG problems
JF – R2019-20

Definitions: (click to show/hide)

No.1489 Adrian Storisteanu

original – 21.03.2020

Solution: (click to show/hide)

Black Kf5 Sf1 Ne1h1

–2(w,b) & h=1                          (0+4)
Circe Assassin
Nightrider e1, h1

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Geoff Foster
Geoff Foster
March 23, 2020 00:36

The notation “[+wQd1,-wQd1]” is a bit confusing. It means that the captured wQ is reborn on d1 and replaces the wQ that is already there. The captured wQ seems to disappear, so it looks like a normal capture (or even a normal Circe capture).

With no animation it is difficult to follow the retractions. Here is what happens:
Qd1xNe1[+bNe1,-wQe1] results in +wQd1
f2xQe1=N[+wQd1,-wQd1] results in +wQe1/+bPf2/-bNe1
Qh2xNh1[+bNh1,-wQh1] results in +wQh2
Sg3xQf1[+wQd1,-wQd1] results in +wQf1/+bSg3/-bSf1

Nikola Predrag
Nikola Predrag
March 24, 2020 03:48

Could this possibly have a meaning without wK?
Which particular ‘game-array’ has no wK?
So, which rules determine the legality of retraction with regards to Circe rebirth?
If a King could have been captured in some retro-moment, then nothing would be retro-illegal.
I just wonder what is a ‘legal’ retro-play from an illegal position?

adrian storisteanu
adrian storisteanu
March 24, 2020 20:44

I hear you. The wK plays no part in the solution, so I didn’t bother. It’s not like we’re trying out the Four Nightriders Defence here. (Maybe white gave K odds, in the spirit of cooperation of a help problem.) Many fairy problems work fine forward in clearly ‘illegal’ positions, this could do it for a few moves backwards without the K (no PG this one). The whole affair is hooey.

A wK could be set on a1 (or several other places where it’s just as irrelevant) to appease the really concerned. These are extraordinary times.

Nikola Predrag
Nikola Predrag
March 24, 2020 23:24

These extraordinary times fake making sense out of nonsense 🙁

‘few moves backwards’??
Supposedly ‘legal play’ ending in an illegal diagram position???

Nevermind, these are indeed extraordinary times 🙂

Kjell Widlert
Kjell Widlert
March 25, 2020 00:23

I find it perfectly possible to interpret the stipulation such that the position arose in a game from SOME starting position, not necessarily the orthodox PAS (in this case, obviously not that). Fairy chess should not be dependent on the orthodox game.

But then, of course, you cannot have a solution that depends on positions like wBa1 + wPb2 being illegal. Those pieces may very well have been there in the unknown starting position.

Nikola Predrag
Nikola Predrag
March 25, 2020 04:18

A ‘joke problem’ provokes solver to guess/recreate the AUTHOR’S rules.
But the fundamental essence of a regular chess problem is the clear rules, such as a SOLVER sees them.
If Circe-rebirth relies on the standard ‘game array’, both Kings are included.

Now, the author BELIEVES that the missing wK is irrelevant for the clarity of rules. And there’s the trouble – either that belief should be IMPOSED to everyone or the problem is incorrect in principle.

Certainly not a big deal in this one particular case (a spectacular composition), but dropping the principles once, may lead to unexpected deformities in the future.

François Labelle
François Labelle
March 25, 2020 16:00

So far, everyone took for granted that a king cannot disappear in the course of a game, but is it really the case in Circe Assassin? Popeye forbids a side from assassinating their own king, but is it really an established rule? Take for example the condition Andernach Rex Inclusive. One might expect that this implies that kings cannot capture, but there are problems by Bedrich Formanek (The Problemist Jan 1996, correction in Sept 1996 issue) where kings capture and change side.

About “dropping the principles once”, it seems it has already occurred. A PDB search for stip=’letzte Zug’ and k=’Platzwechselcirce’ returns a few problems (all by the same author) which are not 16+16. The principle is of course important for other problems, like P1338695.

Nikola Predrag
Nikola Predrag
March 25, 2020 17:31

It’s about the principle as I see it. Of course, there are different views, but some common reasonable agreement is desirable.

Apart from the ‘joke problems’, it’s the solver who interprets the given rules.
The authors (and editors) should provide the unambiguous definitions, leaving no room for different solver’s interpretations.

For instance, adding ‘no wK’ under the diagram could suffice. And it would not be just the obvious fact about the diagram.
‘no wK’ would affect all articles of the rules. In this particular case, that would mean ‘no wK’ in the ‘game array’ with all consequences related to other articles.

“Dropping the principles once” requires ruling for the future cases.