This predicate is provided mainly for compatibility with IC solver. If you intend to impose the same bounds on multiple variables, it is more efficient to use the lib(gfd) specific gfd_vars_impose_min/2 (which additionally does not call wake).
Primitive for updating the upper and lower bounds of Var, As with impose_min/2 and impose_max/2, it is intended for use in implementing co-operation with other solvers, and constraint propagators at the ECLiPSe level, and should not be called from ordinary user code (use ::/2 instead). Its semantics is essentially:
impose_min(Var, Lo), impose_max(Var, Hi), wake.