PhyslibAlpha.ProbabilisticTheory.JordanOrderUnit.JB.GeneratedByOne.Closed
The closed subalgebra generated by one observable
i. Overview
The closure `C(a)` of the subalgebra generated by `1` and `a` in a JB-algebra is closed under the Jordan product, because the product is continuous. It is complete, and associative since the subalgebra generated by one element is. So `C(a)` is a commutative real Banach algebra.
ii. Key results
- `NormedJordanAlgebra.closedGeneratedByOne` : the closed subalgebra generated by `a`.
- `NormedJordanAlgebra.mul_mem_closedGeneratedByOne` : it is closed under the Jordan product.
- `NormedJordanAlgebra.assoc_of_mem_closedGeneratedByOne` : the product is associative on it.
- `NormedJordanAlgebra.ClosedGeneratedByOne` : it as a commutative normed algebra.
iii. Table of contents
- A. The closure
- B. Closure under the Jordan product
- C. Completeness
- D. The bundled commutative normed algebra
A. The closure
B. Closure under the Jordan product
C. Completeness
D. The bundled commutative normed algebra
19 declarations
Closed Jordan subalgebra generated by and
For an element in a normed Jordan algebra over , this definition defines as the topological closure of the -submodule generated by the identity element and . The submodule is the span of the set of Jordan powers , where .
For any element in a normed Jordan algebra over , the -submodule generated by the Jordan powers (where ) is contained within its topological closure .
For any element in a normed Jordan algebra , the identity element belongs to the closed Jordan subalgebra generated by and .
For any element in a normed Jordan algebra , is an element of the closed Jordan subalgebra generated by the identity element and .
is Closed under the Jordan Product
Let be a normed Jordan algebra. For any element , let denote the topological closure of the subalgebra generated by the identity element and . For any elements , if and , then their Jordan product is also an element of .
The Jordan product is associative on
Let be a normed Jordan algebra and be an element in . Let denote the closed -submodule generated by the identity element and , which is the topological closure of the span of the Jordan powers . For any elements , the Jordan product is associative, satisfying .
is a closed set
Let be a normed Jordan algebra and let . The set , defined as the topological closure of the -submodule generated by the identity element and the element (the span of the Jordan powers ), is a closed set in .
is complete
Let be a normed Jordan algebra that is complete (i.e., a JB-algebra). For any element , the subalgebra —defined as the topological closure of the -submodule generated by the identity element and —is complete.
Closed Jordan subalgebra generated by and
For an element in a normed Jordan algebra , this definition denotes the type representing the norm-closed Jordan subalgebra generated by the identity and . Although the multiplication in the ambient algebra is generally non-associative, the multiplication restricted to this subtype is associative, making a commutative real Banach algebra.
Multiplication on the closed Jordan subalgebra
The closed Jordan subalgebra generated by the identity and an element is equipped with a multiplication operation. For any , the product is defined as the Jordan product inherited from the ambient normed Jordan algebra .
Multiplication in coincides with the Jordan product in
Let be a normed Jordan algebra and . Let be the norm-closed Jordan subalgebra generated by the identity and . For any elements , the product computed within is equal to the Jordan product of their corresponding elements in the ambient algebra .
Identity element
For an element in a normed Jordan algebra , the closed Jordan subalgebra generated by the identity and is equipped with a multiplicative identity element, denoted as . This element corresponds to the identity element of the ambient algebra .
The identity element of is the identity element of
Let be a normed Jordan algebra and . Let be the closed Jordan subalgebra generated by the identity element and . The identity element of the subalgebra is equal to the identity element of the ambient algebra .
is a commutative ring
The closed Jordan subalgebra generated by an element and the identity in a normed Jordan algebra forms a commutative ring. While the Jordan product in the ambient algebra is generally non-associative, its restriction to is associative, satisfying for all , alongside the standard axioms of a commutative ring.
is an -algebra
The closed Jordan subalgebra generated by an element and the identity in a normed Jordan algebra is an algebra over the real numbers . This algebra structure is inherited from the ambient algebra , where the scalar multiplication for and is defined by the scalar multiplication in , and the unit map is given by .
is a normed ring
For an element in a normed Jordan algebra , the closed Jordan subalgebra generated by the identity and forms a normed ring. The norm on is inherited from and is submultiplicative, satisfying for all , where the product is the restricted Jordan product.
is a normed -algebra
For an element in a normed Jordan algebra , the closed Jordan subalgebra generated by the identity and is a normed algebra over the real numbers . This means the -algebra structure on is compatible with the norm inherited from , specifically satisfying the property for all scalars and elements .
Completeness of implies completeness of
Let be a normed Jordan algebra. If is a complete space, then for any element , the closed Jordan subalgebra generated by the identity and is also a complete space.
in Equals the -th Jordan Power in
Let be a normed Jordan algebra and . Let be the norm-closed Jordan subalgebra generated by and . For any element and any natural number , the -th power of computed within the commutative ring structure of is equal to the -th Jordan power of computed in the ambient algebra . That is, , where is defined by and .
