Structure Constants
The three-dimensional Bianchi spaces each admit a set of three Killing vectors which obey the following property:
where, the "structure constants" of the group, form a constant order-three tensor antisymmetric in its lower two indices. For any three-dimensional Bianchi space, is given by the relationship
where is the Levi-Civita symbol, is the Kronecker delta, and the vector and diagonal tensor are described by the following table, where gives the ith eigenvalue of ; the parameter a runs over all positive real numbers:
Bianchi type | notes | ||||
---|---|---|---|---|---|
I | 0 | 0 | 0 | 0 | describes Euclidean space |
II | 0 | 1 | 0 | 0 | |
III | 1 | 0 | 1 | -1 | the subcase of type VIa with |
IV | 1 | 0 | 0 | 1 | |
V | 1 | 0 | 0 | 0 | has a hyper-pseudosphere as a special case |
VI0 | 0 | 1 | -1 | 0 | |
VIa | 0 | 1 | -1 | when, equivalent to type III | |
VII0 | 0 | 1 | 1 | 0 | has Euclidean space as a special case |
VIIa | 0 | 1 | 1 | has a hyper-pseudosphere as a special case | |
VIII | 0 | 1 | 1 | -1 | |
IX | 0 | 1 | 1 | 1 | has a hypersphere as a special case |
Read more about this topic: Bianchi Classification
Famous quotes containing the word structure:
“A special feature of the structure of our book is the monstrous but perfectly organic part that eavesdropping plays in it.”
—Vladimir Nabokov (18991977)