These obviously depend on two parameters, a and b, whereas the isomorphism classes of such curves have only one parameter.
By convention, each such isomorphism class is represented by the rule with the lowest code number in it.
Then one may ask, when are two given objects isomorphic and ask for a "particularly nice" representative in each isomorphism class.
There are four isomorphism class of graphs, also shown at the right.
Assume that for each the isomorphism classes of objects in the fiber p(A) form a set.
A finer invariant is needed to detect isomorphism classes.
These isomorphism classes are sets and make up a set in NFU.
This is a proper class model because the strongly cantorian isomorphism classes do not make up a set.
The isomorphism classes can be understood in a simpler way as well.
An isomorphism class is a collection of mathematical objects isomorphic to each other.