🚀 go-pugleaf

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Bastiaan Naber wrote:
>
> I would like to know
> if I could turn GNU Chess into a move validator for 2 human players.
> I would create an interface with php. Is there any document that I
> can use on how to do this ? I searched the web but I could not find
> anything. I found pychess but that is a python module and I don't
> think it will be easy to include that in my website.

Yes, you could, start with a recent copy though as the reporting of
illegal moves was implemented in 5.04, previously it didn't work fully
in Xboard mode.

Read the Engine interface protocol spec at www.tim-mann.org (or in the
xboard source tar ball).

You'll probably want xboard mode (xboard) and pondering off (easy) (to
save CPU).

Use "force" to tell the engine to just read the moves in and echo them
out if legal.

But something like....

$ gnuchess --xboard
Chess
Adjusting HashSize to 1024 slots
force
e5
Illegal move: e5
e4
1. e4
e4
Illegal move: e4
e5
1. e5
Ng3
Illegal move: Ng3
Nf3
2. Nf3
exit

I think if you check the archive you'll find a couple of sites using GNU
Chess either as opponent or move validator.

You need game history to validate moves accurately (castling, ep, draws
by repetition and 50 move rule), so a system that loads the game in from
scratch each time might be best.

E.g. Each game is kept in a PGN file.... One instance of GNU Chess is
running, the command is something like

gnuchess
xboard
easy
force
pgnload 1.pgn
e4
1. e4
pgnsave 1.pgn
pgnload 4.pgn
Nf3
12. Nf3
pgnsave 4.pgn

You might want to rework a command like pgnsave to load game history and
move in one command or some such, but check out the protocol
specification first.

If there are minor changes you need to make life easier shout. I am
planning to add a command line "easy" and one or two extra settings to
the command line. I think draw detection isn't automatic in force mode
(3rd repetition), but that should be easy to fix (hint: we store
position hash values in the move history when loading games).

Done right you might even get several engines working as validators? You
could offer features via "bk" and "hint" commands, although GNU needs to
be thinking for hint to work, but it is your CPU to burn ;-)

There may be better ways !
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