RAT -- the hom-sets of rational maps between two multi-projective varieties

Methods that use a hom-set :

• isMember(MultirationalMap,RAT) -- test membership in a hom-set of rational maps
• RAT List -- define a multi-rational map
• RAT MultiprojectiveVariety -- rational map defined by a linear system of hypersurfaces through a variety
• RAT Sequence -- see RAT MultiprojectiveVariety -- rational map defined by a linear system of hypersurfaces through a variety
• RAT Tally -- rational map defined by an effective divisor

For the programmer

The object RAT is a type, with ancestor classes HashTable < Thing.