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Researchers chip away at Smale's 7th unsolved problem in mathematics

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Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#11
post #9

Earlier quoted context omitted.

Not sure. For n points on a sphere, you're trying to prove a global minimum a very bumpy function over 2n-dimensional space. It may become computationally intractable.

And even if you can find a numerical solution to arbitrary precision, at best you only get arbitrarily close to the mathematically optimal solution ( at best because a purely numerical approach cannot rule out that it misses a very small, but high peak in the function to be optimized) As an extreme example, for n=2 and using binary floating point, you probably will find the mathematically correct solution, but there'…

For N=8 the solution listed on the Wikipedia page is a square antiprism (https://en.m.wikipedia.org/wiki/Square_antiprism) which seems intuitively reasonable. But, I don't see anything listed for N=20. Look at the table in S.5 of the article (https://en.m.wikipedia.org/wiki/Thomson_problem#Configuratio...) for more links to visualisations in the rightmost column, if one exists.

Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#12
post #4

Earlier quoted context omitted.

Those are the best known configurations, we don't have proofs that they are the lowest possible.

Isn't this an optimization problem that can be solved with computer to solve a high degree equation?

The unsolved problem referred to in the title is finding a configuration close to the global minimum. Most optimization algorithms need such a configuration as a starting point.

Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#13
post #9

Earlier quoted context omitted.

Not sure. For n points on a sphere, you're trying to prove a global minimum a very bumpy function over 2n-dimensional space. It may become computationally intractable.

And even if you can find a numerical solution to arbitrary precision, at best you only get arbitrarily close to the mathematically optimal solution ( at best because a purely numerical approach cannot rule out that it misses a very small, but high peak in the function to be optimized) As an extreme example, for n=2 and using binary floating point, you probably will find the mathematically correct solution, but there'…

The function here has a simple continuity, so there is no risk of narrow peaks beyond some computable threshold. The challenge is the high dimensionality.

Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#14
post #3

I actually was asked this problem in a programming interview. This is first I've read that it is an unsolved problem, which definitely makes me chuckle.

I guess if you give someone a puzzle, there's a possibility they might solve the puzzle from memory. If you give an unsolved problem, you know they won't have seen the solution before and can see their thought process better(since you know thinking will be required).

Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#15
post #11
post #9

Earlier quoted context omitted.

And even if you can find a numerical solution to arbitrary precision, at best you only get arbitrarily close to the mathematically optimal solution ( at best because a purely numerical approach cannot rule out that it misses a very small, but high peak in the function to be optimized) As an extreme example, for n=2 and using binary floating point, you probably will find the mathematically correct solution, but there'…

For N=8 the solution listed on the Wikipedia page is a square antiprism ( https://en.m.wikipedia.org/wiki/Square_antiprism ) which seems intuitively reasonable. But, I don't see anything listed for N=20. Look at the table in S.5 of the article ( https://en.m.wikipedia.org/wiki/Thomson_problem#Configuratio... ) for more links to visualisations in the rightmost column, if one exists.

[deleted]

Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#16
post #3

I actually was asked this problem in a programming interview. This is first I've read that it is an unsolved problem, which definitely makes me chuckle.

So ... first whiteboard hazing, then unsolved problems. What's next to get a job writing CRUD apps?

Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#17
post #3

I actually was asked this problem in a programming interview. This is first I've read that it is an unsolved problem, which definitely makes me chuckle.

The exact phrasing matters too, I guess. There are lots of ways to find a good packing, and even good bounds on how far your good packing is from the global optimizer. So a reasonable question to your interviewer would have been "does it need to be the exact global optimizer, or can it be a good approximation ?". If they wanted a good approximation it might not be a bad question, and the question may have been designed to get you to ask for the distinction? Or maybe they were just dicks, who knows.

Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#18
post #3

I actually was asked this problem in a programming interview. This is first I've read that it is an unsolved problem, which definitely makes me chuckle.

Reminds me of reading about at least one case where a problem was solved in a situation like that. Anyone recall what it was?

Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#19
post #3

I actually was asked this problem in a programming interview. This is first I've read that it is an unsolved problem, which definitely makes me chuckle.

Reminds me of reading about at least one case where a problem was solved in a situation like that. Anyone recall what it was?

Dantzig solved an open problem in statistics which he thought was being causally assigned as homework:

https://en.wikipedia.org/wiki/George_Dantzig#Mathematical_st...

Re: Researchers chip away at Smale's 7th unsolved problem in mathematics

#20
post #19

Earlier quoted context omitted.

Reminds me of reading about at least one case where a problem was solved in a situation like that. Anyone recall what it was?

Dantzig solved an open problem in statistics which he thought was being causally assigned as homework: https://en.wikipedia.org/wiki/George_Dantzig#Mathematical_st...

I think you mean "casually", not "causally" (even though it's kind the interesting Freudian slip, IMHO).
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