
( 3 points) In this problem we work out step-by-step the procedure for checking an equivalence relation. Denote by Z the set of all integers. Declare that two integers x,y are related if x+y is an integer multiple of 8 . In symbols: x?y?8 divides x+y. We want to check if this is an equivalence relation. That means we need to check if ? is (1) Reflexive (2) Symmetric (3) Transitive We begin with (1). This means checking to make sure that for all integers x, we have x?x. Recall the definition of ? for this problem and we see that this is equivalent to saying that for all integers x, we have that (x+x) is an integer multiple of 8 . Is this true? If so, enter Y; if not, enter an integer for which this is false. Next, we check (2). This means checking to make sure that for all integers x,y, we have x?y?y?x. Unwind the definition of ? as we have done for (1) and we see that x?y?=8m for some integer m y?x?=8m for some integer m Based on that, is (2) true? If so, enter Y; if not, enter a pair of integers for which this is false. Finally, we check (3). This means checking to make sure that for all integers x,y,z, if x?y and y?z then x?z. Is this true? If so, enter Y; if not, give a triple of integers for which this fails. Finally, based on this calculation, is ? an equivalence relation on the set of integers? Enter Y or N.