Author: Bruce Moreland
Date: 13:08:23 07/12/01
Go up one level in this thread
On July 12, 2001 at 15:57:51, Dann Corbit wrote: >On July 12, 2001 at 15:25:21, Bruce Moreland wrote: > >>On July 12, 2001 at 13:53:01, Dann Corbit wrote: >> >>>However, the previous sentence says "if and only if" and therefore it is >>>required at all times. If a capture can be made, then there is an opposing side >>>pawn. If a capture cannot be made there is none. I also verified the meaning >>>with Steven J. Edwards. At any rate, I have asked him to change the meaning for >>>the next iteration of the standard. >> >>If I say "A is true if B is true", A is true if B is true, and A is undefined if >>B is false. >> >>If I say "A is true if and only if B is true", A is true if B is true, and A is >>false if B is false. But if A is false, that doesn't mean that B is false, >>which is what you contend. > >If and only if means not only that a implies b, but also that b implies a. >Hence, if the flag is set, then the pawn moved two squares. If the pawn moved >two squares then the flag is set. On the other hand, the language is a bit >ambiguous. I can see how alternative interpretations could spring up. > >>Of course, if the author of the document says that that's what he meant, then >>the meaning is clarified. >> >>But to specify that you *must* set the EP square to e3 on 1. e4 is dumb, and I >>wouldn't do it. >> >>It's troubling that two important standards are in the hands of someone who >>doesn't seem to have much time to maintain them, who is not really interested in >>hearing what others have to say about them, and who makes strange and pedantic >>decisions. >> >>I asked him if I could make be involved in discussion of the "new" PGN standard >>(about three years ago), and he essentially told me "no". I can't remember his >>exact reason, but it was something to the effect that he was going to involve >>Bob and other important people. I thought that was very strange. >> >>Meanwhile we have a PGN standard with a billion NAG's, which can't actually be >>used to correctly store an Informant game. > >What's an Informant game? Chess Informants are books full of games, and they've been coming out forever. They use the symbols that you can also see in ECO. ECO uses a logical series of symbols that could have been taken directly, but instead Edwards decided to go them one better by adding "degree" to a lot of them. If you are writing something that eats PGN, converts the NAG's to symbols, and lets the user edit this symbolic text, you have a problem because when you go to output PGN, you have to convert symbols back to NAG's. If the PGN has "white has a small space advantage", "white has a big space advantage", "white has a crushing space advantage", and you turn this into the symbol for "white has a space advantage", when you go to convert it back to the PGN NAG, you don't know which one to convert it to, so you lose information. The NAG set could be a lot more usable in practical cases. As of now, it's pretty bad. bruce
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