Just a definition-question; (about powerset and a set)
So, suppose I have a set \(\color{black}{\small \rm\displaystyle B}\), and a power-set of this set \(\color{black}{\small \rm\displaystyle B}\), denoted as \(\color{black}{\small \rm \displaystyle P(B)}\). Suppose also that \(\color{black}{ \displaystyle x}\) is an arbitrary element in \(\color{black}{ \displaystyle B}\). Is it true then, that \(-\) if \(\color{black}{ \displaystyle x\in B}\) then \(\color{black}{ \displaystyle x\in P(B)}\)?
Short answer is no. Do you see any difference between \(x\) and \(\{x\}\) ?
I think that \({x}\) is an element, and \(\{x\}\) is a set.
Yes, what's the definition of a powerset ?
The set of all possible subsets of the set.
Notice that a subset is a set.
Yes, I know, and that what I was asking \(-\) whether or not \(x\) can also be called a set or not.
because, if not, the statement is false, and if yes, the statement is true.
\(x\) and \(\{x\}\) are two different things. \(x\) is an element, \(\{x\}\) is a set with one element \(x\).
So, \(x\) is definitely \(\color{red}{\bf not}\) a set?
(all I want to verify)
Yes. \(x\not \in P(B)\) The elements of the powerset of B are subsets of B, not elements of B. \(\{x\} \in P(B)\)
I see, so if I make either of the two statements below, the they are false? \(*\) If \(\color{black}{ \displaystyle x\in B}\), then \(\color{black}{ \displaystyle x\in P(B)}\). \(*\) If \(\color{black}{ \displaystyle x\in P(B)}\), then \(\color{black}{ \displaystyle x\in B}\).
Both false
Yes, thank you for confirming! (Now I am ready to go with my proof) Have a nice weekend!
Np, you too have a nice weekend :)
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