Let C(x,y) mean that x is enrolled in y, where the universe of discourse for x is the set of all students in your school and the universe of discourse for y is the set of all classes being given at your school. Express each of the following statements by a simple English sentence.
(upside down E)x (upside down E)y (upside down A)z ((x does not equal y) ^ (C(x,z)->C(y,z)))
(upside down E)x (upside down E)y (upside down A)z ((x does not equal y) ^ (C(x,z)<->C(y,z)))
could be translated as “There are two students, A & B, such that if A is in any class the B is also in the same class”.
Note that saying two students means A is not B.
BTW: It is known in the trade as backwards E not up-side-down.
The old joke is: “How does one translate ”?
Answer: For every up-side-down A there is a backwards E.
So, x does not equal y means that there are two students? That is the part I was confused about. Thank you for your help.