Math Is Fun Forum

666 bro

Member

From: Flatland

Registered: 2019-04-26

Posts: 706

Set theory

How could a null set be an subset of the given set A?

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"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Set theory

hi 666 bro

Introduce a second set B that does not intersect A. 

A intersect B = null set, so the null set must be in A and in B.

This might seem to be just playing with non existent sets but it's safer to assume this is true than trying to re-write the whole of set theory.

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

666 bro

Member

From: Flatland

Registered: 2019-04-26

Posts: 706

Re: Set theory

What would happen if we do union of given set A and an empty set  ?

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"An equation for me has no meaning, unless it expresses a thought of God"- Srinivasa ramanujan

Bob

Administrator

Registered: 2010-06-20

Posts: 10,640

Re: Set theory

What would you have if you had 10 dollars and nothing?

Bob

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Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob