BIOLOGY 1A03 Lecture Notes - Lecture 3: Rock Records, University Of Western Ontario, Empty Set

• School: McMaster University
• Department: Biology
• Course: BIOLOGY 1A03
• Professor: Alastair Tracey

Document Summary

A set is just a collection of, possibly zero, possibly infinitely many objects. {alabama, alaska, wyoming: these are all states. Describe the set using language: eg. The set that contains all canadians who voted ndp in the last election: eg. The set of prime numbers between 10,000 and 100,000. Usually label sets with capital letters (eg. a,b,c) There is one set that has a special name: empty set. Example: let p be the set of inner planets. Sets on their own are static and boring . We want to describe bigger and more complex sets and we"ll often create them from simpler sets. They take old sets and make new sets. Let a and b be sets: a u b: the union of a and b. It is the set that contains exactly the elements which are in either a or b (or in both): a n b: the intersection of a and b.