In mathematics, in the field of functional analysis, an indefinite inner product space
is an infinite-dimensional complex vector space equipped with both an indefinite inner product
and a positive semi-definite inner product
where the metric operator is an endomorphism of obeying
The indefinite inner product space itself is not necessarily a Hilbert space; but the existence of a positive semi-definite inner product on implies that one can form a quotient space on which there is a positive definite inner product. Given a strong enough topology on this quotient space, it has the structure of a Hilbert space, and many objects of interest in typical applications fall into this quotient space.
An indefinite inner product space is called a Krein space (or -space) if is positive definite and possesses a majorant topology. Krein spaces are named in honor of the Soviet mathematician Mark Grigorievich Krein.
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In mathematics, in the field of functional analysis, an indefiniteinnerproductspace ( K , ⟨ ⋅ , ⋅ ⟩ , J ) {\displaystyle (K,\langle \cdot ,\,\cdot \rangle...
an innerproductspace (or, rarely, a Hausdorff pre-Hilbert space) is a real vector space or a complex vector space with an operation called an inner product...
equipped with an indefinite non-degenerate bilinear form, called the Minkowski metric, the Minkowski norm squared or Minkowski innerproduct depending on...
and only if the surface is singular. Indefiniteinnerproductspace – generalization of Hilbert space with indefinite signaturePages displaying wikidata...
translations which is equipped with an innerproduct. The action of translations makes the space an affine space, and this allows defining lines, planes...
mathematics, the indefinite orthogonal group, O(p, q) is the Lie group of all linear transformations of an n-dimensional real vector space that leave invariant...
in an orthonormal basis over a real innerproductspace. The corresponding object for a complex innerproductspace is a Hermitian matrix with complex-valued...
inner product with an indefinite signature. However, one can still define generalized rotations which preserve this innerproduct. Such generalized rotations...
inequality, plays a prominent role in Hilbert space theory, where the left hand side is interpreted as the innerproduct of two square-integrable functions f and...
H} is a complex Hilbert space and ( ⋅ , ⋅ ) {\displaystyle (\cdot ,\cdot )} is given by the imaginary part of the inner-product, the CCR algebra is faithfully...
are global isometries if and only if they are surjective. In an innerproductspace, the above definition reduces to ⟨ v , v ⟩ = ⟨ A v , A v ⟩ {\displaystyle...
lying in the three-dimensional space, does not represent a path of a point rotating as described with the sandwiched product with the versor. Indeed, it...
satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric...
(respectively right) Clifford multiplication by a with respect to this innerproduct. That is, ⟨ a x , y ⟩ = ⟨ x , a t y ⟩ , {\displaystyle \langle ax,y\rangle...
Hermitian product is preserved by all rotations, and therefore is canonical. If, however, the signature of the innerproduct on 3-space is indefinite (i.e...
research on the issue of how humans can survive and work in space for extended and possibly indefinite periods of time. This question requires input from the...
}u|xv{\rangle }_{\mathcal {H}}\qquad {\text{for all }}u,v\in S_{x}} is an indefiniteinnerproduct on S x {\displaystyle S_{x}} of signature ( p , q ) {\displaystyle...
semi-definite innerproducts. The asymptotic state space is then the Hilbert space obtained by quotienting BRST-exact states out of the Krein space. To summarize:...