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From "Sebastian Schelter (JIRA)" <>
Subject [jira] [Commented] (GIRAPH-157) Vertex to perform graph coloring on simple, connected, undirected graphs and related test.
Date Thu, 07 Jun 2012 17:45:23 GMT


Sebastian Schelter commented on GIRAPH-157:


the whole purpose of complexity theory is to identify the problems computable in acceptable
(polynomial) time on today's computers. Out of these problems only those for which we know
algorithms with linear runtime can be scaled to very large datasets. I think you are wasting
your time, if you implemented a nonpolynomial algorithm.

You should ask yourself why you couldn't find a large graph where the chromatic number is
known, maybe it has something to do with the problem being NP-complete???
> Vertex to perform graph coloring on simple, connected, undirected graphs and related
> ------------------------------------------------------------------------------------------
>                 Key: GIRAPH-157
>                 URL:
>             Project: Giraph
>          Issue Type: Test
>          Components: examples, test
>    Affects Versions: 0.2.0
>            Reporter: Eli Reisman
>            Assignee: Eli Reisman
>            Priority: Trivial
>              Labels: newbie
>         Attachments: GIRAPH-157-2.patch, GIRAPH-157.patch
> Hi. I am attempting to learn the Hadoop and Giraph codebases and wanted to write a simple
client application for Giraph to help me learn the ins and outs of it. This is a simple unit
test and vertex modeled after the ConnectedComponentsVertex and related test. The vertex test
runs whenever you run the "mvn test" or "mvn verify" suite of tests. When finished processing,
each vertex will have an integer value that is its color.
> This is a pretty simple implementation, and although I have tested it on a number of
small graphs of varied trickiness and it seems to rapidly arrive at a minimal coloring, its
hard (for me at least) to guess which possible coloring it will arrive at and I have no idea
how it will do on really big graphs yet without finding some more pre-colored larger test
graphs to try it on. Ideas anyone?
> Anyway, it was fun to put this together, and I'd be happy to improve it or receive some
help or advice to further the cause. Thanks again, I am hoping this will be the first of many
(hopefully more useful) contributions!
> Eli

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