紫◆5. Equivalence relations o Equivalence relations ◆ equivalence class .6.Partial order relations and Hasse Diagrams Extremal elements of partially ordered sets: maximal element. minimal element o greatest element, least element o upper bound, lower bound least upper bound, greatest lower bound o Theorems examples. and exercises 5. Equivalence Relations  Equivalence Relations  equivalence class  6.Partial order relations and Hasse Diagrams  Extremal elements of partially ordered sets:  maximal element, minimal element  greatest element, least element  upper bound, lower bound  least upper bound, greatest lower bound  Theorems, examples, and exercises