src/Pure/term.ML

     | _ => "uu")
   in Abs (x, fastype_of v, abstract_over (v, t)) end;
 
 (*Form an abstraction over a free variable.*)
 fun absfree (a,T,body) = Abs (a, T, abstract_over (Free (a, T), body));
-fun absdummy (T, body) = Abs (Name.internal "x", T, body);
+fun absdummy (T, body) = Abs (Name.internal "uu", T, body);
 
 (*Abstraction over a list of free variables*)
 fun list_abs_free ([ ] ,     t) = t
   | list_abs_free ((a,T)::vars, t) =
       absfree(a, T, list_abs_free(vars,t));