An specific question about propagation.

	Hello,	

	I have this program:

:- lib(fd).

go :-
        AT1 #>=0,
        ST1 #>=0,
        ADur #>=10,
        SDur #>=0,
        ST1 #= AT1,
        ST1 + SDur #>= AT1 + ADur,
        write([AT1,ST1,ADur,SDur]),nl,
        true.

go2 :-
        AT1 #>=0,
        ST1 #>=0,
        ADur #>=10,
        SDur #>=0,
        ST1 #= AT1,
        AT1 + SDur #>= AT1 + ADur, 	% This line is the only one different from go.
        write([AT1,ST1,ADur,SDur]),nl,
        true.

	Executing go, the output is:

	[AT1{[0..10000000]}, AT1, ADur{[10..10000000]}, SDur{[0..10000000]}]

	Executing go2, the output is:

	[AT1{[0..10000000]}, AT1, ADur{[10..10000000]}, SDur{[10..10000000]}]

	I was wondering why the system doesn't reduce SDur's domain in the first case.
	(My experience with ECLiPSe is quite limited.)

	Thanks in advance,

		Oscar Rosell