Originally Posted by

**eddielee** Sorry not much of a maths wiz so I don't even know if I've posted this in the correct section. Apologies if not.

Just doing some revision for a first year maths exam and there is a question on sets and relations asking to determine if something is reflective, symmetric and transitive.

For example

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

Is symmetric and transitive but not reflective. I don't understand how this is worked out. Could some one please explain this to me?