Is there a notation to refer to all the n element subsets of a set? I know the power set denotes all of the subsets.
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3Some people use ${S}\choose{n}$, confer an answer on mathoverflow on suggestions for good notation. – k.stm Mar 10 '14 at 20:33
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That's very nonstandard. I'd go about defining a notation for it, such as $$\mathcal P_n (A) := {O\in\mathcal P(A) | #(O) = n}$$ Where $#$ denotes the number of elements. – AlexR Mar 10 '14 at 20:34
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1I see $[A]^n$ ocasionally. – Marcin Łoś Mar 10 '14 at 20:38
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3@AlexR: ${S}\choose{n}$ is completely standard in combinatorics. – Hans Lundmark Mar 10 '14 at 21:01
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@HansLundmark seeing your reference, I agree (an upvoted mo post seems legitimate ;) ). Forgive my unawareness. – AlexR Mar 10 '14 at 21:03