[Retros] MDR

[raosorio at fibertel.com.ar]

Hi Andrew,

"I have to confess an aesthetic preference for problem forms which are 
"self-defining". With MDR, it appears that there is a codification required for 
each form as to what "opportunities" and "incompletions" are legitimate. I have 
a related kind of trauma about lexical problems, which depend on the language 
used to record the moves. My problem, sorry. "
***************************************************************
why? perhaps dues to tthe fact the explaining article is missing here.
Opportunities are well defined ( leaving your king in check, castling when you
had already loose the right to do it, etc) and incompletions are related to chess
moves that involve more than one piece. All these cases have to be deducted
from the retroanalysis.


"I think the basic principle should be that the solver is required in principle 
to demonstrate whether any position, even a fairy position, is legal. If the 
position is legal, then it can be assumed by the solver that it derives from 
some history (although no reason to assume one history over another). If it is 
illegal, then for a fairy position there is no issue. For an conventional 
position, it acquires the property of fairiness, but there is otherwise no 
issue. "
****************************************************************
MDR tries to present the conventional position not as a fairy one but as
a feseable situation in real game, resulting from a last illegal move
but under control for the retro rhinking.

Roberto


Hi Roberto, 



>Circe problem. Mate? 



I think that the intended answer is "No." Black has just captured Na2, which 
must re-appear like Duncan Idaho on b1 to complete the move and block the 
check. White's prior move can only have been discovered check. 

The key question to be resolved in solving the problem was whether you intended 
overlooking check or mate to be a "legitimate" error. The answer is no, because 
e.g. otherwise Black might just have captured B on a2, and the problem would be 
cooked. 

However this meta-reasoning can now be applied to all other problems of this 
form, which are therefore easier. 

I have to confess an aesthetic preference for problem forms which are 
"self-defining". With MDR, it appears that there is a codification required for 
each form as to what "opportunities" and "incompletions" are legitimate. I have 
a related kind of trauma about lexical problems, which depend on the language 
used to record the moves. My problem, sorry. 

I applaud the attempt to combine fairy + FIDE rules however. Some fairy forms 
(e.g. Circe, maximummer) naturally admit retro logic all the way back to the 
game array. 

Others (e.g. with weird units) do not admit retro logic. We can add the 
convention that the game is otherwise orthodox, but there are extra options for 
pieces to promote to. That convention is an elegant idea which I hadn't come 
across before. If it is already widely adopted, or if it formed part of the 
pre-announcement to the German tournament referred to earlier, then it's 
totally OK to form part of the judging criteria for this tournament. Not sure I 
would want to see it as a default convention though. 

The Codex is not very helpful about all this, stating baldly that fairy 
problems have no history. 

I think the basic principle should be that the solver is required in principle 
to demonstrate whether any position, even a fairy position, is legal. If the 
position is legal, then it can be assumed by the solver that it derives from 
some history (although no reason to assume one history over another). If it is 
illegal, then for a fairy position there is no issue. For an conventional 
position, it acquires the property of fairiness, but there is otherwise no 
issue. 

Best, 
Andrew. 

--- raosorio at fibertel.com.ar wrote: 



> 



> Hi Guus and everybody, 



> 



> "When you think about it, the whole concept is quite similar to MDR but 



> projected in the domain of typographic and pictographic errors" 



> 



> Yes, it is. The MDR convention is an effort to provide an scenario where all 



> the things might be 



> quite subltle. There is a remarkable potential here (I think that the Ke1-g1 



> problem is a good 



> example. Ke1-g1 is a geometrically correct move due to the h1 rook. Without 



> this, this king evolution 



> would not fit with any geometry alllowed by article 3). 



> 



> Look at this Werner's problem, 



> 



> Werner Keym 



> Die Welt 1969 (VI) Die Schwalbe 8 04/1971 



> 1B6/8/4PPPP/4p2P/5k1P/3Q3P/8/6KR 



> #0,5 



> 



> the position contains a very nice retroanalysis, but the stip #0.5 makes the 



> solution evident. 



> MDR provides the following alternative presentation: (How does this end? 



> MDR). 



> 



> Both theses cases belong to the "finalyzed and incomplete move" cathegory. 



> After the 7.4 retraction article 4.6 forces to make the complete move (and 



> then to mate). 



> 



> Best, 



> Roberto 



> 



> 



> Thanks Roberto, I will look at the position. For years I have enjoyed solving 



> the Christmas puzzle in one of our newspapers, for the main reason that there 



> is always one error in it, two in the very good years. Nothing exceeds the 



> satisfaction of finding the errors plus the solutions! Also, this will be 



> last fortress to fall to the computer, a million years from now. One year ago 



> I suggested to the belgium team captain to organize a solving contest based 



> on the intentional error idea. I mentioned options like "omitting a pawn in 



> the diagram", "changing draw to win in the stipulation", "mistyping helpmate 



> for selfmate" (this one I encountered in a recent puzzle) - possibly in a mix 



> with some correct presentations as well. For the requirement to be in special 



> state of mind to solve these problems, I suggest the name "wodka solving 



> contest" for such a competition. When you think about it, the whole concept 



> is quite similar to MDR but projected in the domain of typographic and p 



> ictographic errors. 



> 



> Guus Rol.