I am completely lost on the terminology on this one.
Let be an equivalence relation on a non-empty set X.
Let a X. Show that [a
Here [a := {b X | a b}
Is this supposed to be b=a? What is this set X?
The only thing I get is that X is non-empty so it must contain at least one element b. Then the equivalence relation has to be non-empty by definition of equivalence.
I just found out that we skipped four sections in the textbook. I had not heard of an equivalence relation before and did not know that it is reflexive, symmetric and transitive. I also did not understand that [a] was an equivalence class. So I have some more reading to do. I see the answer you supplied is extremely helpful.
Wish I had you for my professor instead of my current one!
Merry ChrisKwanuka.