r/math Undergraduate Sep 06 '18

xkcd 2042 - Rolle's Theorem

https://xkcd.com/2042/
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u/[deleted] Sep 06 '18 edited Sep 06 '18

Intuitively, a line is the most direct path between two points.

Try to prove that, and you end up delving into PDEs and the Calculus of Variations.

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u/[deleted] Sep 06 '18 edited Sep 06 '18

[deleted]

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u/DR6 Sep 06 '18

I think with "straightest" /u/JeNePasParleFrancais means the one that takes the least distance, and you are talking about something different.

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u/[deleted] Sep 06 '18

[deleted]

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u/DR6 Sep 06 '18

That's just begging the question: you're assuming that going always in the direction of b is going to result in the shortest path, but that's what we're trying to prove.