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| bio | website | yaroslavvb.blogspot.com |
|---|---|---|
| location | Mountain View, CA | |
| age | 32 | |
| visits | member for | 2 years, 9 months |
| seen | Jan 30 at 9:23 | |
| stats | profile views | 379 |
Software Engineer at Google (StreetView/OCR)
Google+ profile
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Feb 25 |
revised |
On the existence of closed form solutions to finite combinatorial problems deleted 29 characters in body |
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Feb 25 |
answered | On the existence of closed form solutions to finite combinatorial problems |
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Feb 20 |
revised |
How to solve transcendental equations with Mathematica 7? deleted 15 characters in body |
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Feb 20 |
answered | How to solve transcendental equations with Mathematica 7? |
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Feb 18 |
comment |
Higher dimensional analog to planar graphs? When you say "triangulation", do you mean representing vertices of a graph as points in the space? I have trouble imagining how tree structured-graphs fit into this construction |
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Feb 18 |
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Higher dimensional analog to planar graphs? Intuitively it seems that such "cell" construction would have bounded doubling dimensions, whereas planar graphs can have unbounded doubling dimension |
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Feb 18 |
answered | Higher dimensional analog to planar graphs? |
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Feb 18 |
accepted | spanning trees as graph homomorphisms |
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Feb 17 |
comment |
spanning trees as graph homomorphisms OK, makes sense (although using G instead of H in second paragraph confused me at first). The reason its interesting is because of the theorem (from linked blog post) that $G_1,G_2$ are isomorphic iff $|\text{Hom}(G_1,H)|=|\text{Hom}(G_2,H)|$, so now it seems that "number of spanning trees" doesn't give any information about the graph that's not captured by "homomorphism definable" invariants like number of independent sets or proper colorings |
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Feb 16 |
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spanning trees as graph homomorphisms I'm interested in representing "number of spanning trees" as number of certain homomorphisms, not sure your comment rules it out. This post gives the motivation for counting graph homomorphisms -- rjlipton.wordpress.com/2011/02/14/… |
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Feb 16 |
asked | spanning trees as graph homomorphisms |
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Feb 3 |
comment |
Best way to exactly solve a linear system (300x300) with integer coefficients That seems to be the case. They may be using a proprietary method which doesn't have a common name. OneStepRow reduction however isn't that bad, about 20 seconds on my laptop for 200x200 matrix with entries in billions and 80% zeros |
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Feb 3 |
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Best way to exactly solve a linear system (300x300) with integer coefficients Out of those ones, "OneStepRowReduction" is the fastest. For 300x300 matrix with -2 billion..2 billion entries, Method->Automatic takes about 2 seconds, "OneStepRowReduction" not sure, but more than a minute. Takes about 6 seconds on 150x150 matrix with such entries, whereas Automatic takes 0.2 seconds |
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Feb 3 |
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Best way to exactly solve a linear system (300x300) with integer coefficients yes, here's the output I got from the code above -- pastebin.com/YY5pptcD |
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Feb 3 |
revised |
Best way to exactly solve a linear system (300x300) with integer coefficients added 37 characters in body; added 271 characters in body |
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Feb 3 |
answered | Best way to exactly solve a linear system (300x300) with integer coefficients |
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Feb 3 |
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Havel & Hakimi degree sequence theory From degrees you can tell if the graph is Eulerian, you can tell if graph is a tree |
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Feb 3 |
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Best way to exactly solve a linear system (300x300) with integer coefficients You can integrate Mathematica functions into C programs using MathLink interface. It's not free. Using Mathematica's library for your task I get answers with denominators 500 digits long, and it takes about 1/2 second on my laptop |
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Feb 3 |
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Best way to exactly solve a linear system (300x300) with integer coefficients I wonder what's special about your matrices that makes results have only 80 digits long denominators. I tried random 300x300 60% sparse matrices with integers between 1 and 10, and typical denominators are around 500 digits long |
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Jan 24 |
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Speeding up Gauss Elimination There's some controversy whether Strassen is practical -- rjlipton.wordpress.com/2010/10/23/galactic-algorithms/… |
