determinism

Could you help to write this program :
det(T,G) succeeds if and only if G succeeds once and only once and give 
the T answer.
1) I don't want the solution below by findall, because I want to try at 
most two back tracks on G.
det(T,G) :- findall(T,G,L),length(L,1)

2) I know already call_det but it's not the solution because G can have 
choice points, but only one answer.



	
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Michel Levy
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