Definition 8
The duality scalar product of a multiform
with a multivector
is the
scalar
defined by the following axioms:
For all
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(9)
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For all
and
(with
)
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(10)
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where
is any pair of dual bases
over
For all
and
if
and
then
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(11)
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Definition 3.1
.
Let
and
be finite groups.
A (free)
-biset
is a set endowed with a free left
-action and a free right
-action, which commute:
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When it is not clear from context which groups act on
, we write
.
Equivalently,
is a left
-set such that the restrictions of the action to
and
are free. This equivalence is formed by setting
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Given a
-biset
the
opposite biset
is the
-biset
with the same underlying set and with action defined by
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If
and
as
-bisets, we say
is
symmetric
.
Denote by
the monoid of isomorphism classes of
-bisets with disjoint union as addition.
If
and
, we define the
-biset
to be
. With
as composition, the monoids
form the morphism sets of a category where the objects are all finite groups. This is also the reason why a
-biset has
acting from the right and not the left, so that the composition order of bisets
fits with the general convention for maps and morphisms.
The
point-stabilizer
of an element
in a
-biset
is
, the subgroup consisting of all pairs
such that
, or equivalently
.
A
(injective)
-pair
is a pair
with
and
an injective group map. If
is a
-pair, denote by
the
-biset
.
If we also denote by
the
graph
of
:
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then
as
-sets.
We will also refer to the graph
as a
twisted diagonal (subgroup)
. In the case that
is a finite
-group,
, and
for a given fusion system
on
, we will refer to
as an
-twisted diagonal (subgroup)
.
The
-pairs
and
are
-conjugate
if there are elements
and
such that
and
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commutes. This happens if and only if the twisted diagonals
and
are conjugate as subgroups of
.
Definition 1.3
(i) A
Hom-associative algebra
is a triple
, in which
is a linear space,
and
are linear maps,
with notation
, such that
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for all
.
We call
the
structure map
of
.
A morphism
of Hom-associative algebras
is a linear map
such that
and
.
(ii) A
Hom-coassociative coalgebra
is a triple
, in which
is a linear
space,
and
are linear maps
(
is called the
structure map
of
) such that
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A morphism
of Hom-coassociative
coalgebras
is a linear map
such that
and
.
Definition 4.2.2
.
Let
be a
-variety. We construct a closed subscheme
of
as follows. Let
be the quotient map, and
the involution of the sheaf of
-algebras
. We consider the morphism
of sheaves of
-vector spaces on
. The subsheaf
of
coincides with
by
[
SGA I
, V, Corollaire 1.2]
, and
. Thus
induces a morphism
. If
is an open subscheme of
, and
, then we have in
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When
, then
, so that
. This proves that
is a morphism of
-modules. Its image is a quasi-coherent sheaf of ideals of
, and we define
as the corresponding closed subscheme of
.
Thus when
, the closed subscheme
is defined by the ideal
of
(
Notation 4.1.1
).
Definition 1.7
.
An
RLC-system
is a triple
such that
is an RC-system,
is a second binary operation on
that obeys the
left-cyclic law
(1.10)
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and both operations are connected by
(1.11)
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An
RLC-quasigroup
is an RLC-system
such that the left-translations of
and the right-translations of
are one-to-one.