Given the set $A=\{1,2,3,4,5,6\}$ how many equivalence relations ( symmetric, reflexive and transitive ) can you form if the following pairs are disallowed: $\{ (3,4),(2,4),(2,3),(1,4),(1,3),(1,2)\}$ ? All six must not be present.
I saw this on a final exam and had no idea how to even approach it.