Question

Major Cartesion product is subset or not
Subset of eqvivalance relation​

Answer 1

Answer:

"a)X=Z the relation ≡n defined as a≡nb⟺n|b−a"

"b) X any set of groups, ≅ “isomorphic to” is an equivalence relation."

Now when I looked online (e.g. Wolfram Alpha) and in a book, they both define an equivalence relation in terms of a "subset, R, of X×X".