I'm having trouble comprehending the concept. For instance, I have this problem, asking whether or not this is an equivalence relation:

R = { (1,1), (1,2), (2,1), (2,2) , (3,3) }

on the set (1, 2, 3}

I understand that for this to be an equivalence relation it must be reflexive, symmetric, and transitive, but I am confused as to how to check for these properties.

For instance, I see reflexive properties in (1,1), (2,2), and (3,3) but not in the others. Is that a problem? And how do I check for transitive and symmetric?