A crazy chained assignment: (%i3) (a : b, b : c, c : d, d : e)$ No facts: (%i4) facts(); (%o4) [] Call simp_given on 1 with one fact a < b (%i5) simp_given(1,a<b); (%o5) 1 And oops--a fact leaked out: (%i6) facts(); (%o6) [d>c] Isn't this a bug? --Barton