The pro-filing has proved its power once more. My complex program has a fragment which generates many arithmetical expressions, filtering out `reducible' ones and nub-bing them with respect to the commutativity of some operators. I expected the `reducible' test to take most of the cost. But the whole program has taken suspiciousely long. The profiling showed that nub_by_commutatitvity (nub) takes 10 times more than the `reducible' test. It was hard to discover this without profiling, because the program has many places to suspect. Then, I tried for this fragment (setToList . mkSet) instead of nub ! The whole test has become faster 8 times! `nub-like' reduced to 0.01; the `reducible' test takes 3/4, as it was initially expected. Quite an adventure. ----------------- Serge Mechveliani mechvel@botik.ru