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# Set theory Watch

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1. NM. Problem done.
2. {a} P({a}) is false.

Why is it false?
3. What's the definition of the powerset?

Use that to write out the set P({a}). Then it's clear.
4. (Original post by Simplicity)
What's the definition of the powerset?

Use that to write out the set P({a}). Then it's clear.
Thanks for your speedy reply. A power set is represented as 2^s, where, s, is the set of all the subsets......

So the power set will be {a} and {}.....a is in the powerset, so I don't see why it's not true? I'm a pretty slow mate, so try to explain it a bit more for me, please.
5. (Original post by boromir9111)
Thanks for your speedy reply. A power set is represented as 2^s, where, s, is the set of all the subsets......

So the power set will be {a} and {}.....a is in the powerset, so I don't see why it's not true? I'm a pretty slow mate, so try to explain it a bit more for me, please.
No,

I see what you miss understand.

{1,2,3} is a subset of {1,2,3,4}

But, you are sort of saying {a} is a subset of {{},{a}}, which it isn't. It is an element through.
6. (Original post by Simplicity)
No,

I see what you miss understand.

{1,2,3} is a subset of {1,2,3,4}

But, you are sort of saying {a} is a subset of {{},{a}}, which it isn't. It is an element through.
Oh. Because a is an element, that's why?
7. (Original post by boromir9111)
Oh. Because a is an element, that's why?
That's too vague.

a is element of of {a}, but isn't an element of {{},{a}}.

So not a subset by definition.

Try to be more precise .
8. Ahh, yes. I was a bit vague but I know what I meant. Thanks mate for your help!

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Updated: December 15, 2010
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