Vertex coloring digraphs and hypergraphs
We present a combinatorial problem that arises naturally
when trying to reduce the storage space in a genetic database, without
loosing certain ``relational properties''. This connects
to vertex colorings of acyclic digraphs and
strong vertex colorings of hypergraphs. Optimizing
such colorings yield some interesting mathematics
on balanced incomplete block designs (BIBDs) and finite geometries.