Burnside Ring - Examples

Examples

The table of marks for the cyclic group of order 6:

Z6 1 Z2 Z3 Z6
Z6 / 1 6 . . .
Z6 / Z2 3 3 . .
Z6 / Z3 2 0 2 .
Z6 / Z6 1 1 1 1

The table of marks for the symmetric group S3 on 3 letters:

S3 1 Z2 Z3 S3
S3 / 1 6 . . .
S3 / Z2 3 1 . .
S3 / Z3 2 0 2 .
S3 / S3 1 1 1 1

The dots in the two tables are all zeros, merely emphasizing the fact that the tables are lower-triangular.

(Some authors use the transpose of the table, but this is how Burnside defined it originally.)

The fact that the last row is all 1s is because is a single point. The diagonal terms are m(H, H) = | NG(H)/H |.

The ring structure of Ω(G) can be deduced from these tables: the generators of the ring (as a Z-module) are the rows of the table, and the product of two generators has mark given by the product of the marks (so component-wise multiplication of row vectors), which can then be decomposed as a linear combination of all the rows. For example, with S3,

as (3, 1, 0, 0).(2, 0, 2, 0) = (6, 0, 0, 0).

Read more about this topic:  Burnside Ring

Famous quotes containing the word examples:

    In the examples that I here bring in of what I have [read], heard, done or said, I have refrained from daring to alter even the smallest and most indifferent circumstances. My conscience falsifies not an iota; for my knowledge I cannot answer.
    Michel de Montaigne (1533–1592)

    It is hardly to be believed how spiritual reflections when mixed with a little physics can hold people’s attention and give them a livelier idea of God than do the often ill-applied examples of his wrath.
    —G.C. (Georg Christoph)

    Histories are more full of examples of the fidelity of dogs than of friends.
    Alexander Pope (1688–1744)