[eclipse-users] Propia question

I'm having a problem with the interaction between lib(ic_sets) and lib 
(propia):

:- lib(ic).
:- lib(ic_sets).
:- lib(propia).

adjacent(1,2).

:- integers([F,T]), adjacent(F, T) infers ac.

gives:

Ambiguous import of :: / 2 from [ic, ic_sets] in module eclipse
calling an undefined procedure F :: 1 .. 1 in module eclipse

The code works fine if I remove lib(ic_sets). Any suggestions?

Malcolm

--
"The modern man in revolt has become
           practically useless for all purposes of revolt.
By rebelling against everything
           he has lost his right to rebel against anything."
                                                    - G.K.Chesterton,  
Orthodoxy