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Vector partition function

The project has been evolving since March 2010 into a semisimple Lie algebra online calculator

hosted at UMass Boston
hosted at Jacobs University.

The calculator is still completely experimental (use at your own risk).

Computations of vector partitions

The online computation of vector partition functions is down at the moment, will be restored, with an online interface only.

Developers

To join this project, contact Todor Milev, todor.milev at google's email.

The calculator page contains a non-tested description of how to try to install the calculator on your machine. Requires understanding of C++. You are cordially invited to use the source code however you wish (under the usual Library General Public License).

Computations with simple Lie algebras

The program has functions working with semisimple Lie algebras. For example it computes html tables with the root subsystems of simple root systems of rank<=8. Root subsystems parametrize the reductive root subalgebras of a simple Lie algebra (a root subalgebra is defined as a subalgebra containing a Cartan subalgebra). The calculator also includes tables with one representative of each conjugacy class of complex sl(2)-subalgebras of a simple Lie algebra, computed according to the algorithm described in Dynkin's paper "Semisimple Lie subalgebras of semisimple Lie algebras".

Here is a list of some of the structure theory of the semisimple subalgerbas of the simple Lie algebras of rank 8 or less as computed by the calculator.

Structure constants Semisimple subalgebras sl(2) subalgebrasroot subalgebras
F4 F4 semisimple subalgebras F4 sl(2) triples F4 root subalgebras
E6 E6 semisimple subalgebras E6 sl(2) triples E6 root subalgebras
E7 Not available E7 sl(2) triples E7 root subalgebras
E8 Not available E8 sl(2) triples E8 root subalgebras
G2 G2 semisimple subalgebras G2 sl(2) triples G2 root subalgebras
A1 A1 semisimple subalgebras A1 sl(2) triples A1 root subalgebras
A2 A2 semisimple subalgebras A2 sl(2) triples A2 root subalgebras
A3 A3 semisimple subalgebras A3 sl(2) triples A3 root subalgebras
A4 A4 semisimple subalgebras A4 sl(2) triples A4 root subalgebras
A5 A5 semisimple subalgebras A5 sl(2) triples A5 root subalgebras
A6 A6 semisimple subalgebras A6 sl(2) triples A6 root subalgebras
A7 Not available A7 sl(2) triples A7 root subalgebras
A8 Not available A8 sl(2) triples A8 root subalgebras
D4 D4 semisimple subalgebras D4 sl(2) triples D4 root subalgebras
D5 Not available D5 sl(2) triples D5 root subalgebras
D6 Not available D6 sl(2) triples D6 root subalgebras
D7 Not available D7 sl(2) triples D7 root subalgebras
D8 Not available D8 sl(2) triples D8 root subalgebras
B2 B2 semisimple subalgebras B2 sl(2) triples B2 root subalgebras
B3 B3 semisimple subalgebras B3 sl(2) triples B3 root subalgebras
B4 B4 semisimple subalgebras B4 sl(2) triples B4 root subalgebras
B5 Not available B5 sl(2) triples B5 root subalgebras
B6 Not available B6 sl(2) triples B6 root subalgebras
B7 Not available B7 sl(2) triples B7 root subalgebras
B8 Not available B8 sl(2) triples B8 root subalgebras
C3 C3 semisimple subalgebras C3 sl(2) triples C3 root subalgebras
C4 C4 semisimple subalgebras C4 sl(2) triples C4 root subalgebras
C5 C5 semisimple subalgebras C5 sl(2) triples C5 root subalgebras
C6 Not available C6 sl(2) triples C6 root subalgebras
C7 Not available C7 sl(2) triples C7 root subalgebras
C8 Not available C8 sl(2) triples C8 root subalgebras

The calculator also gives matrices of finite dimensional simple representations of simple complex Lie algebras. The dimension must be small enough, effectively up to around 200. For example, here is the 27 dimensional irreducible representation of the Lie algebra G_2 (to the left you will find an "info expand/collapse" button/link, there are the matrices giving of the Lie algebra G_2 action): hwv{}(G_2, (2,0),(0,0));

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A Root system visualization in javascript. Try projecting the root system of B3 (so(7)) onto G2! (hint: try to put the 1st and 3rd basis vector on top of one another).

Select root system.

The basis vectors correspond to the vertices of the Dynkin diagram.
You can drag the center and the basis vectors.

The root system in simple basis coordinates follows.



Project Information

Acknowledgements. Many thanks to Thomas Bliem for setting up the SVN repository (August 2009)! Many thanks to the IT department of Jacobs Univesity for hosting the calculator software, as well as for setting up and supporting the Apache web server (March 2010)! Many thanks to Madan Chaudhary and his website for the javascript autocomplete code in the online calculator (August 2011)!

About this project:

This is the Vector partition function project ("vectorpartition")

This project was registered on SourceForge.net on May 21, 2009.

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