Isometric continuous functional calculus #
This file adds a class for an isometric continuous functional calculus. This is separate from the
usual ContinuousFunctionalCalculus
class because we prefer not to require a metric (or a norm) on
the algebra for reasons discussed in the module documentation for that file.
Of course, with a metric on the algebra and an isometric continuous functional calculus, the
algebra must be a C⋆-algebra already. As such, it may seem like this class is not useful. However,
the main purpose is to allow for the continuous functional calculus to be a isometric for the other
scalar rings ℝ
and ℝ≥0
too.
Isometric continuous functional calculus for unital algebras #
An extension of the ContinuousFunctionalCalculus
requiring that cfcHom
is an isometry.
- predicate_zero : p 0
Instances
Isometric continuous functional calculus for non-unital algebras #
An extension of the NonUnitalContinuousFunctionalCalculus
requiring that cfcₙHom
is an
isometry.
- predicate_zero : p 0
- exists_cfc_of_predicate (a : A) : p a → ∃ (φ : ContinuousMapZero (↑(quasispectrum R a)) R →⋆ₙₐ[R] A), Topology.IsClosedEmbedding ⇑φ ∧ φ { toContinuousMap := ContinuousMap.restrict (quasispectrum R a) (ContinuousMap.id R), map_zero' := ⋯ } = a ∧ (∀ (f : ContinuousMapZero (↑(quasispectrum R a)) R), quasispectrum R (φ f) = Set.range ⇑f) ∧ ∀ (f : ContinuousMapZero (↑(quasispectrum R a)) R), p (φ f)