MACM 101 Lecture 13: Lecture 13 Part 1_ Operations on Sets

• School: Simon Fraser University
• Department: Math & Comp Sci
• Course: MACM 101
• Professor: Andrei Bulatov

Document Summary

Often it is convenient to visualize various relations between sets. The intersection of sets a and b, denoted by a b, is the set that contains those elements that belong to both a and b. A b = { x | x a x b} The union of sets a and b, denoted by a b, is the set that contains those elements that are in. Sets a and b are said to be disjoint if a b = . | a b | = | a | + | b | - | a b | To count elements in a b we first count elements of a, then elements of b. Elements of a b are counted twice, so, we subtract the number of such elements. If a and b are disjoint, then | a b | = | a | + | b |