2006-11-22: Updated OCamlMakefile.

2006-07-26: Improved documentation.

2004-07-01: Fixed is_empty-function.  It now uses the newly available
            Map.is_empty function.

            Updated OCamlMakefile.

2004-04-19: Added split-function to ptset.

            Updated OCamlMakefile.

2003-11-23: Updated OCamlMakefile.

2003-01-07: Updated OCamlMakefile to make use of "findlib".

2002-12-03: Replaced union1 and union2 with one union-function only.
            Replaced inter1 and inter2 with one inter-function only.

2002-09-25: Fixed example: it had mistakenly been changed during some
            test application so that it did not do what it was supposed
            to do.

2002-09-11: Updated OCamlMakefile and license.

            Documented all modules for use with ocamldoc.

2002-05-04: Revised the whole installation procedure. See INSTALL for
            details.

2002-04-30:  Updated OcamlMakefile: it does not ask for confirmation
             during installation anymore!

2002-04-04: Renamed pretty-printing functions for consistency.

2002-03-08: Added new functions to pomap (see interface documentation
            for details):

             * take
             * take_ix
             * choose
             * filter
             * partition
             * fold_split_eq_classes
             * preorder_eq_classes
             * topo_fold_reduced

2002-02-27: Added new functions to pomap (see interface documentation
            for details):

              * cardinal
              * singleton
              * add_node
              * remove_node
              * mem_ix
              * find_ix
              * topo_fold_ix
              * rev_topo_fold_ix
              * union1, union2
              * inter1, inter2
              * diff
              * fold_eq_classes

            Added new functions to store:

              * cardinal
              * singleton

            Slightly modified the Hasse-example.

            Updated OcamlMakefile.

2002-02-18: Added new functions to pomap (see interface documentation
            for details):

              * remove_eq_prds
              * rev_topo_fold, rev_topo_foldi
              * rev_chain_fold, rev_chain_foldi

            Slightly extended the Hasse-example.

2002-02-04: Fixed bug in function "is_empty".

            Added functions "chain_fold" and "chain_foldi", which fold
            over chains of ascending elements (see interface for details).

            Updated OcamlMakefile.

2001-08-01: Fixed tiny bug in example "hasse".

2001-07-31: Changed order of arguments for a few functions to make them
            more similar to set/map-functions in the standard
            library. Sorry for the inconvenience!

2001-07-30: Added more modules to "pomap": they contain functionality
            to generate specifications for the dot-utility to render
            Hasse-diagrams. This functionality is now factored out of
            the Hasse-example. See the following files for documentation:

              lib/display_hasse_intf.mli
              lib/display_hasse_impl.mli

            The Hasse-example now demonstrates this functionality.

2001-07-27: Incompatible change: "get_graph" was removed, "get_nodes"
            introduced (with a slightly different type).

2001-07-26: Added function "create_node".

2001-07-26: Tiny optimization.

2001-07-24: Incompatible change: the "Added"-constructor returned by
            "add_find" now also tells you the added node. This was
            important, because it could be interesting to know the
            neighbours of a newly inserted node.

2001-07-18: Added functions "topo_fold" and "topo_foldi" that fold
            over elements in topological order.

2001-07-17: First release.