Definition 2.4
.
If
is a real-valued analytic function of
in a neighborhood of
,
we define
the sign of
at
to be the sign of the first nonvanishing Taylor series coefficient
(around
), if there
is such, and zero otherwise. In other words, if
, we have:
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where
for
and
.
Definition 2.1
A
Courant algebroid
is a
vector bundle
with
a Loday bracket on
,
i.e., an
-bilinear map satisfying the
Jacobi identity,
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for all
,
an anchor,
, which is a morphism of vector bundles,
and
a field of non-degenerate symmetric bilinear forms
on the
fibers of
,
satisfying
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for all
,
and
.
Definition 2
A Lie algebroid
is a vector bundle
together with a bundle map (“anchor”)
and
a Lie algebra structure
satisfying the Leibniz identity
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(9)
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.
Definition 2.1
.
An orthomodular lattice (
OML
) is
an algebraic structure
in which
the following conditions are satisfied for any
:
L1.
L2.
L3.
L4.
L5.
L6.
L7.
L8.
where
,
.
Also
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and the implications
are defined
as follows
(Sasaki)
(Dishkant)
(Kalmbach)
(non-tollens)
(relevance)
Definition 2
(Quaternion Algebras)
.
Let
be a field of characteristic
. For
,
let
be the
-algebra with basis
(as an
-vector space) and with multiplication rules
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Then
is an
-algebra which is called a
quaternion algebra
over
.
Definition 1.1
A
Poisson algebra
over the field
is a commutative algebra
over
equipped with an additional skew-linear operation
such that
(1.1)
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for all
. An ideal
is called a
Poisson ideal
if
for any
,
.