> I have a need for an algorithm to perform "subsumption" on partially > ordered sets of values. That is, given a selection of values from a > partially ordered set, remove all values from the collection that > are less than some other member of the collection.
That is, you want the maxima, right? The following seems to work, though I don't know how efficient it is. maxima :: (Eq a) => [[Maybe a]] -> [[Maybe a]] maxima es = maxima' [] es where maxima' ms [] = ms maxima' ms (e:es) = maxima' (add ms e) es add [] e = [e] add (m:ms) e = case pcompare m e of PNR -> m:(add ms e) PGT -> m:ms PLT -> add ms e PEQ -> m:ms Cheers Robert _______________________________________________ Haskell-Cafe mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/haskell-cafe