Let A be a unital C^(∗)-algebra and B a unital C^(∗)-algebra with a faithful traceτ.Let n be a positive integer.We give the definition of weakly approximate diagonalization(with respect toτ)of a unital homomorphism...Let A be a unital C^(∗)-algebra and B a unital C^(∗)-algebra with a faithful traceτ.Let n be a positive integer.We give the definition of weakly approximate diagonalization(with respect toτ)of a unital homomorphismφ:A→Mn(B).We give an equivalent characterization of McDuff Ⅱ_(1) factors.We show that,if A is a unital nuclear C^(∗)-algebra and B is a type Ⅱ_(1) factor with faithful traceτ,then every unital^(∗)-homomorphism φ:A→M_(n)(B)is weakly approximately diagonalizable.If B is a unital simple infinite dimensional separable nuclear C^(∗)-algebra,then any finitely many elements in Mn(B)can be simultaneously weakly approximately diagonalized while the elements in the diagonals can be required to be the same.展开更多
A linear mappingφfrom an algebra A into its bimodule M is called a centralizable mapping at G∈A ifφ(AB)=φ(A)B=Aφ(B)for each A and B in A with AB=G.In this paper,we prove that if M is a von Neumann algebra without...A linear mappingφfrom an algebra A into its bimodule M is called a centralizable mapping at G∈A ifφ(AB)=φ(A)B=Aφ(B)for each A and B in A with AB=G.In this paper,we prove that if M is a von Neumann algebra without direct summands of type I1 and type II,A is a*-subalgebra with M■A■LS(M)and G is a fixed element in A,then every continuous(with respect to the local measure topology t(M))centralizable mapping at G from A into M is a centralizer.展开更多
Suppose A is a unital C＊-algebra and r 1.In this paper,we define a unital C＊-algebra C（cb）＊（A,r） and a completely bounded unital homomorphism αr：A → C（cb）＊（A,r）with the property that C（cb）＊（A,r）=C...Suppose A is a unital C＊-algebra and r 1.In this paper,we define a unital C＊-algebra C（cb）＊（A,r） and a completely bounded unital homomorphism αr：A → C（cb）＊（A,r）with the property that C（cb）＊（A,r）=C＊（αr（A））and,for every unital C＊-algebra B and every unital completely bounded homomorphism φ：A→ B,there is a（unique）unital ＊-homomorphism π：C（cb）＊（A,r）→B such thatφ=πoαr.We prove that,if A is generated by a normal set {tλ：λ∈Λ},then C（cb）＊（A,r）is generated by the set {αr（tλ）：λ∈Λ}.By proving an equation of the norms of elements in a dense subset of C（cb）＊（A,r）we obtain that,if Β is a unital C＊-algebra that can be embedded into A,then C（cb）＊（B,r）can be naturally embedded into C（cb）＊（A,r）.We give characterizations of C（cb）＊（A,r）for some special situations and we conclude that C（cb）＊（A,r）will be ＂nice＂ when dim（A）≤ 2 and ＂quite complicated＂ when dim（A）≥ 3.We give a characterization of the relation between K-groups of A and K-groups of C（cb）＊（A,r）.We also define and study some analogous of C（cb）＊（A,r）.展开更多
基金supported by the Natural Science Foundation of Chongqing Science and Technology Commission(Grant No.cstc2020jcyj-msxmX0723)the Research Foundation of Chongqing Educational Committee(Grant No.KJQN2021000529)supported by the National Natural Science Foundation of China(Grant Nos.11871127,11971463)。
文摘Let A be a unital C^(∗)-algebra and B a unital C^(∗)-algebra with a faithful traceτ.Let n be a positive integer.We give the definition of weakly approximate diagonalization(with respect toτ)of a unital homomorphismφ:A→Mn(B).We give an equivalent characterization of McDuff Ⅱ_(1) factors.We show that,if A is a unital nuclear C^(∗)-algebra and B is a type Ⅱ_(1) factor with faithful traceτ,then every unital^(∗)-homomorphism φ:A→M_(n)(B)is weakly approximately diagonalizable.If B is a unital simple infinite dimensional separable nuclear C^(∗)-algebra,then any finitely many elements in Mn(B)can be simultaneously weakly approximately diagonalized while the elements in the diagonals can be required to be the same.
基金supported by National Natural Science Foundation of China(Grant Nos.1180100511801342+6 种基金118010041187102111801050)supported by a Startup Fundation of Anhui Polytechnic University(Grant No.2017YQQ017)supported by Shaanxi Provincial Education Department(Grant No.19JK0130)supported by Research Foundation of Chongqing Educational Committee(Grant No.KJQN2018000538)We would like to thank the for their patience and useful comments.
文摘A linear mappingφfrom an algebra A into its bimodule M is called a centralizable mapping at G∈A ifφ(AB)=φ(A)B=Aφ(B)for each A and B in A with AB=G.In this paper,we prove that if M is a von Neumann algebra without direct summands of type I1 and type II,A is a*-subalgebra with M■A■LS(M)and G is a fixed element in A,then every continuous(with respect to the local measure topology t(M))centralizable mapping at G from A into M is a centralizer.
基金partially supported by a Collaboration Grant from the Simons Foundation
文摘Suppose A is a unital C＊-algebra and r 1.In this paper,we define a unital C＊-algebra C（cb）＊（A,r） and a completely bounded unital homomorphism αr：A → C（cb）＊（A,r）with the property that C（cb）＊（A,r）=C＊（αr（A））and,for every unital C＊-algebra B and every unital completely bounded homomorphism φ：A→ B,there is a（unique）unital ＊-homomorphism π：C（cb）＊（A,r）→B such thatφ=πoαr.We prove that,if A is generated by a normal set {tλ：λ∈Λ},then C（cb）＊（A,r）is generated by the set {αr（tλ）：λ∈Λ}.By proving an equation of the norms of elements in a dense subset of C（cb）＊（A,r）we obtain that,if Β is a unital C＊-algebra that can be embedded into A,then C（cb）＊（B,r）can be naturally embedded into C（cb）＊（A,r）.We give characterizations of C（cb）＊（A,r）for some special situations and we conclude that C（cb）＊（A,r）will be ＂nice＂ when dim（A）≤ 2 and ＂quite complicated＂ when dim（A）≥ 3.We give a characterization of the relation between K-groups of A and K-groups of C（cb）＊（A,r）.We also define and study some analogous of C（cb）＊（A,r）.
