src/HOL/Tools/Function/context_tree.ML

       val num_branches = map_index (apsnd branch_vars) (prems_of crule)
     in
       IntGraph.empty
         |> fold (fn (i,_)=> IntGraph.new_node (i,i)) num_branches
         |> fold_product (fn (i, (c1, _)) => fn (j, (_, t2)) => 
-               if i = j orelse null (gen_inter (op =) (c1, t2))
+               if i = j orelse null (inter (op =) (c1, t2))
                then I else IntGraph.add_edge_acyclic (i,j))
              num_branches num_branches
     end
     
 val default_congs = map (fn c => c RS eq_reflection) [@{thm "cong"}, @{thm "ext"}]