  This work is concerned with regular languages defined over large alphabets,
either infinite or just too large to be expressed enumeratively. We define a
generic model where transitions are labeled by elements of a finite partition
of the alphabet. We then extend Angluin's L* algorithm for learning regular
languages from examples for such automata. We have implemented this algorithm
and we demonstrate its behavior where the alphabet is a subset of the natural
or real numbers. We sketch the extension of the algorithm to a class of
languages over partially ordered alphabets.
