Small typo in program-14.15.

Hello,

program-14.15:58 should read

lookup(X,[(X1,V1)|XVs],V) :- X \= X1, lookup(X,XVs,V).

(with '\=' instead of '\==').

With '\==', Elisa loops forever if a stimulus contains a variable (i.e. a number) but that the rest of the Input does not match (at least, this is the behavior with SWI).

Regards,
Didier P.