partial isometry

См. также в других словарях:

• Partial isometry — In functional analysis a partial isometry is a linear map W between Hilbert spaces H and K such that the restriction of W to the orthogonal complement of its kernel is an isometry. We call the orthogonal complement of the kernel of W the initial… …   Wikipedia

• Isometry — For the mechanical engineering and architecture usage, see isometric projection. For isometry in differential geometry, see isometry (Riemannian geometry). In mathematics, an isometry is a distance preserving map between metric spaces. Geometric… …   Wikipedia

• Polar decomposition — In mathematics, particularly in linear algebra and functional analysis, the polar decomposition of a matrix or linear operator is a factorization analogous to the polar form of a nonzero complex number z where r is the absolute value of z (a… …   Wikipedia

• Singular value decomposition — Visualization of the SVD of a 2 dimensional, real shearing matrix M. First, we see the unit disc in blue together with the two canonical unit vectors. We then see the action of M, which distorts the disk to an ellipse. The SVD decomposes M into… …   Wikipedia

• Semigroup with involution — In mathematics, in semigroup theory, an involution in a semigroup is a transformation of the semigroup which is its own inverse and which is an anti automorphism of the semigroup. A semigroup in which an involution is defined is called a… …   Wikipedia

• Von Neumann algebra — In mathematics, a von Neumann algebra or W* algebra is a * algebra of bounded operators on a Hilbert space that is closed in the weak operator topology and contains the identity operator. They were originally introduced by John von Neumann,… …   Wikipedia

• Subnormal operator — In mathematics, especially operator theory, subnormal operators are bounded operators on a Hilbert space defined by weakening the requirements for normal operators. Some examples of subnormal operators are isometries and Toeplitz operators with… …   Wikipedia

• Self-adjoint operator — In mathematics, on a finite dimensional inner product space, a self adjoint operator is one that is its own adjoint, or, equivalently, one whose matrix is Hermitian, where a Hermitian matrix is one which is equal to its own conjugate transpose.… …   Wikipedia

• Quasinormal operator — In operator theory, quasinormal operators is a class of bounded operators defined by weakening the requirements of a normal operator. Definition and some properties Definition Let A be a bounded operator on a Hilbert space H , then A is said to… …   Wikipedia

• Trigonometric moment problem — In mathematics, the trigonometric moment problem is formulated as follows: given a finite sequence { α 0, ... αn }, does there exist a positive Borel measure mu; on the interval [0, 2 pi; ] such that:alpha k = frac{1}{2 pi}int 0 ^{2 pi} e^{… …   Wikipedia

• Extensions of symmetric operators — In functional analysis, one is interested in extensions of symmetric operators acting on a Hilbert space. Of particular importance is the existence, and sometimes explicit constructions, of self adjoint extensions. This problem arises, for… …   Wikipedia