The table of marks of a finite group records the numbers of group
fixed points for the transitive group actions
of
on cosets
of its subgroups. Let
,
,
...,
be representatives of the conjugacy classes of
subgroups of
.
The table of marks is the
matrix
with
Thus
is the number of fixed points of
in the transitive action of
on the right cosets of
(Burnside 1955).
If the subgroup classes are ordered compatibly with containment up to conjugacy, the table is a lower triangular matrix.
Its th
diagonal entry is the subgroup index
of
in its normalizer, so the
table is a nonsingular matrix. Since every
transitive permutation action of
is equivalent to a group action
on the cosets of a subgroup, invertibility allows the multiplicities of the transitive
constituents of a finite
-set
to be recovered from its fixed-point counts. The table also encodes containment information
among conjugacy classes of subgroups (GAP).
For example, using the class order ,
,
,
, the table of marks of the symmetric
group
is
Tables of marks were introduced by Burnside and are consequently also called Burnside matrices.