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Universal Method to Sort Complex Information Found

quantamagazine.org

1–10 of 68 posts

Re: Universal Method to Sort Complex Information Found

#2
The subtitle claims that a “universal way” was found to solve the nearest-neighbour-search problem for any kind of data, but actually the result is restricted to the (rather huge, of course) set of normed spaces, i.e. spaces whose distance measures obey the triangle inequality.

Re: Universal Method to Sort Complex Information Found

#3
Ah that's so cool. I've been reading about expander graphs lately. Their interesting properties make them pertinent to lots of questions. In particular, you can use expander graphs to cook up error correcting codes and prove the PCP theorem. There's a class of expander graphs called Ramanujan graphs which are characterized by an analogue to the Riemann hypothesis involving a zeta function that counts the prime cycles in a graph.

Re: Universal Method to Sort Complex Information Found

#4

The subtitle claims that a “universal way” was found to solve the nearest-neighbour-search problem for any kind of data, but actually the result is restricted to the (rather huge, of course) set of normed spaces, i.e. spaces whose distance measures obey the triangle inequality.

It's a rather large set, but it's got some noteworthy holes. Cosine distance, for example.

Re: Universal Method to Sort Complex Information Found

#5

The subtitle claims that a “universal way” was found to solve the nearest-neighbour-search problem for any kind of data, but actually the result is restricted to the (rather huge, of course) set of normed spaces, i.e. spaces whose distance measures obey the triangle inequality.

Incidentally, the zone system for the Danish public transit system is not a metric space. (The ticket you need from A to B is not necessarily the same as from B to A.)

That's a kind of practical graph where you want efficient shortest path algorithms for.

Re: Universal Method to Sort Complex Information Found

#7
post #5

The subtitle claims that a “universal way” was found to solve the nearest-neighbour-search problem for any kind of data, but actually the result is restricted to the (rather huge, of course) set of normed spaces, i.e. spaces whose distance measures obey the triangle inequality.

Incidentally, the zone system for the Danish public transit system is not a metric space. (The ticket you need from A to B is not necessarily the same as from B to A.) That's a kind of practical graph where you want efficient shortest path algorithms for.

[deleted]

Re: Universal Method to Sort Complex Information Found

#9

The subtitle claims that a “universal way” was found to solve the nearest-neighbour-search problem for any kind of data, but actually the result is restricted to the (rather huge, of course) set of normed spaces, i.e. spaces whose distance measures obey the triangle inequality.

> spaces whose distance measures obey the triangle inequality

That would be a metric space, and a distance obey the triangle inequality by definition. The element of the space are otherwise quite arbitrary.

Unfortunately, Normed spaces are a subset of metric spaces which are much less general (in particular they have to be vector spaces).

Re: Universal Method to Sort Complex Information Found

#10
post #5

The subtitle claims that a “universal way” was found to solve the nearest-neighbour-search problem for any kind of data, but actually the result is restricted to the (rather huge, of course) set of normed spaces, i.e. spaces whose distance measures obey the triangle inequality.

Incidentally, the zone system for the Danish public transit system is not a metric space. (The ticket you need from A to B is not necessarily the same as from B to A.) That's a kind of practical graph where you want efficient shortest path algorithms for.

Really?? Is that true only when there are multiple paths between A & B or is there something else involved?
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