15 Mar 05
Originally posted by THUDandBLUNDERThere is a difference (maybe just symantics?) in illegal and possible.
And no pieces or pawns have been captured.
So how did the pawns pass each other?
ATY said the position is not illegal, you are saying it is just not possible.
The question I have then, is: Is the position illegal, or just impossible (or both?)
15 Mar 05
Originally posted by AlcraI would say that a position is illegal if it cannot be arrived at by a series of legal moves.
There is a difference (maybe just symantics?) in illegal and possible.
ATY said the position is not illegal, you are saying it is just not possible.
The question I have then, is: Is the position illegal, or just impossible (or both?)
15 Mar 05
2 edits
Originally posted by AThousandYoungSomewhat predicably, USCF gives a less-than-useful definition:
I say impossible but legal.
Illegal position - A position in which both Kings are in check or a number of factors are involved which make a position illegal.
http://www.uschess.org/beginners/glossary.php
But the definition is clear in the world of chess problems (which is what I posted).
Legal position (n.): a position that can be reached from the initial array by a game consisting entirely of legal moves, however bizarre. Conventionally, any chess problem should have a legal position. Naturally then, an illegal position is a position that cannot be reached by a legal game. (Oxford Companion to Chess).
See also Article 8 of FIDE Laws.
http://www.chessvariants.com/fidelaws.html
15 Mar 05
Originally posted by THUDandBLUNDERAll right then. I bow down to your superior researching efforts. It's illegal! Give yourself a ticket, THUDandBLUNDER!!
Somewhat predicably, USCF gives a less-than-useful definition:
Illegal position - A position in which both Kings are in check or a number of factors are involved which make a position illegal.
http://www.uschess.org/beginners/glossary.php
But the definition is clear in the world of chess problems (which is what I posted).
Legal position (n.): a ...[text shortened]... n to Chess).
See also Article 8 of FIDE Laws.
http://www.chessvariants.com/fidelaws.html
15 Mar 05
Originally posted by THUDandBLUNDERIt does matter. As your source pointed out, most compositions begin from legal positions. Can you really claim you have given checkmate if the position was not legal to start with? In a game, the opponent may able to have the game replayed from the last legal position. An excellent defense against 'forced' mate!
I don't think the definition matters too much.
If legality is deliberately shirked, it makes the problem 'unorthodox' and more like a 'fairy' problem (even though I hate that term).
16 Mar 05
Originally posted by BigDoggProblemIMO, it matters for games.
It does matter. As your source pointed out, most compositions begin from legal positions. Can you really claim you have given checkmate if the position was not legal to start with? In a game, the opponent may able to have the game replayed from the last legal position. An excellent defense against 'forced' mate!
If legality is deliberately shirke ...[text shortened]... kes the problem 'unorthodox' and more like a 'fairy' problem (even though I hate that term).
Less so for problems unless they are retros.
In fact, I think I will post a few of my favourites.