Call the forms and compatible if
(2.1) |
for all . An alternating trilinear form is nondegenerate if there exists a compatible nondegenerate symmetric bilinear form on .
is a unital associative algebra with generators , , , , and defining relations
(5) | ||||
is the factor algebra of over the ideal generated by the relation .
is a unital associative algebra with generators , , , , , and defining relations ( 5 ) and
(16) |
is a real form of equipped with an anti–involution * defined on generators by
(28) |
and are the factor algebras of over the ideals generated, respectively, by the relations and .
The q–oscillator algebra is a unital associative algebra with generators , , , and defining relations , and
(78) |
and equipped with an anti–involution * defined on generators by
(79) |
The Weyl algebra is a unital associative algebra with generators , , , and defining relations and
(102) |
and equipped with an anti–involution * defined on generators by
(103) |
(Symmetric system) Let be a set with a (not necessarily associative) multiplication
Then the pair is called a symmetric system if the following conditions are satisfied for all , and :
By abuse of language, we will sometimes say that is a symmetric system instead of saying that is a symmetric system. If for all and then we call the trivial multiplication . If and we write if , and .
In a monoidal category with neutral object E , a monoid is a triple made of an object , a morphism called the product and a morphism called the unit. These morphisms should satisfy the two following relations:
(14) | |||
(15) |
We call the couple a monoid structure on .
Let , and let be the cone of classes in such that
for all .
The circular measure of a rooted bipartite graph is given by
where is the real measure.
A Hom-associative algebra over is a triple where is a bilinear map and is a linear map, satisfying
(1.1) |
A Hom-Leibniz algebra is a triple consisting of a linear space , bilinear map and a homomorphism satisfying
(1.3) |
A - Hom-cochain is a map , where satisfying
(5.1) |
We denote by the set of all - Hom-cochain of .
Let be a harmonic function in . We denote by its conjugate harmonic function and we set
Let and define a -module structure by
where is the augmentation map.
Let be defined by . We call exceptional if . For every we define integers and by the rule
(Supporting mountains) Fix . A mountain refers to any function on of the form
with . The mountain is said to be focused at . The mountain is said to support at if and
for all . The mountain is said to support to first order at if , and has a manifold structure near with
(A.1) |
Given a valued field , define a -restricted exponential to be an isomorphism of groups between the valuation ideal of and the -units of (with respect to ) which is -compatible ; that is,
Let be an algebra with automorphism . Let be a -derivation that satisfies
for all . The Ore extension of associated with data is a ring , containing as a subring, generated by elements in and a new variable and subject to the relation
(E1.1.1) |
for all . The Ore extension ring is denoted by .
Functional ( 6 ) is said to be invariant under the one-parameter family of infinitesimal transformations
(25) |
if and only if
for any subinterval .
The extended nil Hecke ring is the smashed product of by . As a -module, it is just the tensor product . The multiplication is defined by
An operation , where , is a weak near-unanimity function if is idempotent and
for all .
Let be a complex manifold with a holomorphic -vector . If the Schouten bracket vanishes, i.e., , we call a (holomorphic) Poisson structure on and the Poisson bracket is defined by
[Monodromy around a boundary circle:] Let be a -cover of . Consider the th boundary circle, , where the base point on is and the point on the fiber above is . This has an orientation which comes from the orientation of the surface. Let be a parameterization of the boundary circle which also preserves the orientation of . We also assume that . Then there is a unique lifting of to the -cover, say such that . We define the monodromy, , of this th boundary circle to be that unique element of such that
(1) |
representation!projective A projective representation of on is a function such that for every , there exists a constant such that
(3.1) |