What is a Subset?

Date: 10/13/2001 at 20:51:26
From: phillip kutsen
Subject: What is a subset

I would like to know what a subset is.

Thank you.

Date: 10/13/2001 at 21:46:04
From: Doctor Achilles
Subject: Re: What is a subset

Hi Phillip,

Thanks for writing to Dr. Math.

A set is just a group of things that you write down in a list. In 
math, you usually put {} around a set, and commas between items in the 
set.  

You can have a set of numbers, such as {1, 2, 5, -9, 2.63}, or a set 
of variables such as {x, a, m, y, z}, or a set of objects {table, 
desk, chair, computer}. You can even have mixed sets such as {couch, 
TV, 8, elephant, 2, -97, 55.2, 3x}.

Let's say I have two sets. I'll call one of them "set1" and one of 
them "set2".  set2 is a subset of set1 if everything in set2 is also 
in set1.

So for example, the set {1, 2, 3} is a subset of the set {1, 2, 3, 4, 
8}. And {elephant} is a subset of {couch, TV, 8, elephant, 2, -97, 
55.2, 3x}. 

You can also have an empty set {}, which is a subset of all sets.

I hope this helps. If you have any other questions, let me know, and 
I'd be happy to talk about this with you some more.

- Doctor Achilles, The Math Forum
  http://mathforum.org/dr.math/