Knowledge graphs are so under-utilised for practical things despite the fact that there is significant amount of useful research out there. Their problem is that they are expensive. I hope further research in ML would help elevate their relevance significantly. I am particularly fond of using knowledge graphs and graph theory for security related work.
A new algorithm for graph crossings, hiding in plain sight (2020)
21–30 of 44 posts
Re: A new algorithm for graph crossings, hiding in plain sight (2020)
#22The previously best known algorithm for deciding if a given edge could be added to a planar n-node graph, while keeping it planar, took time O(sqrt(n)). The new algorithm needs time only O((log n)^3), an exponential speedup.
How? But, yeah, for large graphs it should be (somewhat) faster.
Re: A new algorithm for graph crossings, hiding in plain sight (2020)
#23The previously best known algorithm for deciding if a given edge could be added to a planar n-node graph, while keeping it planar, took time O(sqrt(n)). The new algorithm needs time only O((log n)^3), an exponential speedup.
https://www.wolframalpha.com/input/?i=graph+ln%28n%29%5E3+vs...
Re: A new algorithm for graph crossings, hiding in plain sight (2020)
#24The previously best known algorithm for deciding if a given edge could be added to a planar n-node graph, while keeping it planar, took time O(sqrt(n)). The new algorithm needs time only O((log n)^3), an exponential speedup.
This really only takes effect for very large values of n. The crossover is around 3x10^7 https://www.wolframalpha.com/input/?i=graph+ln%28n%29%5E3+vs...
Re: A new algorithm for graph crossings, hiding in plain sight (2020)
#25I like graph theory. You draw some shapes, you draw some lines. It's like the kind of things you can do with your crayons. I reckon kids could be introduced to it earlier in friendlier language.
Re: A new algorithm for graph crossings, hiding in plain sight (2020)
#26Earlier quoted context omitted.
This really only takes effect for very large values of n. The crossover is around 3x10^7 https://www.wolframalpha.com/input/?i=graph+ln%28n%29%5E3+vs...
In fairness, that's not _that_ huge of a graph.
Re: A new algorithm for graph crossings, hiding in plain sight (2020)
#27The previously best known algorithm for deciding if a given edge could be added to a planar n-node graph, while keeping it planar, took time O(sqrt(n)). The new algorithm needs time only O((log n)^3), an exponential speedup.
This really only takes effect for very large values of n. The crossover is around 3x10^7 https://www.wolframalpha.com/input/?i=graph+ln%28n%29%5E3+vs...
- C1 = C2 = 1 => cross-over is 2x10^7
- C1 = 1, C2 = 10 => cross-over is 2x10^10
- C1 = 10, C2 = 1 => cross-over is 1668.2!
Re: A new algorithm for graph crossings, hiding in plain sight (2020)
#28Re: A new algorithm for graph crossings, hiding in plain sight (2020)
#29Of course the constant terms matter, but sqrt(N) < log2(N)^3 up until billions of nodes. For 2*32 nodes sqrt(N) is 2^16 and log2(N)^3 is 2^15. We deal with graphs of that size in electronic design automation, and planar graphs don't need metal crossovers, but we aren't adding one connection at a time. So this result in itself isn't going to be terribly applicable, but may lead to further insights and development of i…
I work with the researchers, and I think they'll be interested in knowing which version of the problem practitioners like yourself are most interested in. Do you ever add/remove edges, perhaps in bulk? Or do are you mostly interested in finding "best possible" layouts for static datasets?
Re: A new algorithm for graph crossings, hiding in plain sight (2020)
#30Earlier quoted context omitted.
n=nodes>0; n^0.5=(log n)^3, n~24128091.7 , which is millions not billions? https://www.wolframalpha.com/input/?i=sqrt%28n%29%3D%28log+n...
You're using natural log, for my quick-and-dirty I used log2, which gives a slightly higher crossover point. The exact crossover depends on the size of the constant term, of course.