Let $C$ be the collection of all cardinal numbers. Is there any norm, inner-product, metric (other than discrete metric), topology(other than discrete, co-finite topology) on $C$, which is very useful?
After studying little bit about the cardinal numbers, it seems that the cardinal numbers are very important concept for viewing the sets, specially for the infinite sets. Together with the algebra of cardinal numbers, is there analysis of cardinal numbers?
May be my question is so poor!
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