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cardinality of sets

cooldudeman

quick q, with sets like {1,{2,6},5,7} what is the size/cardinality?

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Reply 1

Damask-

Four. The set contains the numbers 1, 5 and 7, and the set containing 2 and 6.

Reply 2

cooldudeman

Original post by Damask-

Four. The set contains the numbers 1, 5 and 7, and the set containing 2 and 6.

does cardinality means the no. of elements in a set? if it does then {2,6} is counted as an element?

Reply 3

Smaug123

Original post by cooldudeman

does cardinality means the no. of elements in a set? if it does then {2,6} is counted as an element?

Yes. If I were to look at the set element-by-element, I would see 1, then the set {2,6}, then 5, then 7. It might be more clearly stated as follows:
The cardinality of the set {cat, 3, {6, dog}, pi} is 4, because its elements are cat, 3, the set {6,dog}, and pi.

Reply 4

Boucly

Think of a set as a folder in your laptop. Cardinality is the number of files, including other folders, that you can see when you open that folder.
Edit: um.. for finite sets, that is. Infinite number of files is kinda bad.