Hacker Newsnew | past | comments | ask | show | jobs | submitlogin

Convergent sequences are always Cauchy; for metric spaces, compactness and sequential compactness are the same.


I think the question is more like:

> Turing says that a certain space, the space of all compact subsets of [0,1]^2 endowed with the metric "integral of minimal distance required to transform {1 ink at each point of P1} u {infinite amount of ink at (2, 0)} into {1 ink at each point of P2} u {infinite amount of ink at (2,0)}", is conditionally-compact. How is that related to the article's argument?

This is not obvious, I think. The article has moved away from Turing's "integral of the distance we have to transfer ink", instead using "maximum distance we have to transfer any ink", and I don't have a great intuition for whether this is a legit transformation of the argument. (I'm sure both proofs are correct, but it's not obvious to me that they are the same proof.)


Yes and yes, but conditional compactness is different, and Cauchy sequences are not always convergent. That's why I mentioned completeness.




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: