Which ofthese relations on the set of all people are

Chapter 8, Problem 8.5.2

(choose chapter or problem)

Which ofthese relations on the set of all people are equivalence relations? Determine the properties of an equivalence relation that the others lack. a) {(a, b) I a and b are the same age} b) {(a, b) I a and b have the same parents} c) {(a, b) I a and b share a common parent} d) {(a, b) I a and b have met} e) {(a, b) I a and b speak a common language}