Abstract:
In this paper we investigate the dependence of recursively enumerable
structures on the equality relation which is fixed to a specific
r.e. equivalence relation. We compare r.e. equivalence relations on the
natural numbers with respect to the amount of structures they permit
to represent from a given class of structures such as algebras, permutations
and linear orders. In particular, we show that for various types
of structures represented, there are minimal and maximal elements.