Mathematics

Mathematics

Problem

On the set of integers Z\mathbb Z, define R={(a,b):a−b is divisible by 3}R=\{(a,b):a-b\text{ is divisible by }3\}. Which of the following statements about RR is correct? a) RR is reflexive, symmetric and transitive b) RR is reflexive and symmetric only c) RR is symmetric and transitive only d) RR is reflexive, symmetric, transitive and antisymmetric
Intuitive explanation

This problem asks you to recognize that RR is a congruence relation — a way of grouping integers that behave the same way modulo 3. The key insight is that RR partitions Z\mathbb{Z} into three equivalence classes (remainders 0, 1, and 2 when divided by 3), and you should check whether RR is reflexive, symmetric, transitive, or some combination. Think about what it means for (a,b)∈R(a,b) \in R: does every integer relate to itself? If aa relates to bb, does bb relate to aa? If aa relates to bb and bb relates to cc, does aa relate to cc?

Intuitive explanation

This problem asks you to recognize that RR is a congruence relation — a way of grouping integers that behave the same way modulo 3. The key insight is that RR partitions Z\mathbb{Z} into three equivalence classes (remainders 0, 1, and 2 when divided by 3), and you should check whether RR is reflexive, symmetric, transitive, or some combination. Think about what it means for (a,b)∈R(a,b) \in R: does every integer relate to itself? If aa relates to bb, does bb relate to aa? If aa relates to bb and bb relates to cc, does aa relate to cc?

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