Concept guide
Equivalence relation: checking the three axioms on a complete finite relation and emitting the classes
On X={0,1,2,3,4} the relation R is listed completely as 13 ordered pairs: (0,0), (1,1), (2,2), (3,3), (4,4), (0,2), (2,0), (1,3), (3,1), (1,4), (4,1), (3,4), (4,3). Check reflexivity, symmetry and transitivity item by item, prove that R is an equivalence relation and emit its classes; then show that R′, obtained by removing (3,4) and (4,3), is reflexive and symmetric but not an equivalence relation.