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Examples of Sets

Set of Living People

Let $P$ denote the set of living people.


\(\ds \text {The person reading this web page}\) \(\in\) \(\ds P\)
\(\ds \text {Julius Caesar}\) \(\notin\) \(\ds P\)
\(\ds -4\) \(\notin\) \(\ds P\)

Positive Integers Less than 10

The (strictly) positive integers less than $10$ form a set:

$\set {1, 2, 3, 4, 5, 6, 7, 8, 9}$

People Called Smith

The collection of people whose surname is Smith form a set.