scholarly journals Minimal index of a $C^{*}$-crossed product by a finite group

2000 ◽  
Vol 129 (7) ◽  
pp. 2031-2038
Author(s):  
Ja A Jeong ◽  
Gie Hyun Park
Keyword(s):  
Finite Group ◽  
Crossed Product ◽  
Minimal Index ◽  
A Finite Group

scholarly journals CONJUGATE PAIRS OF SUBFACTORS AND ENTROPY FOR AUTOMORPHISMS

2011 ◽  
Vol 22 (04) ◽  
pp. 577-592 ◽  
Author(s):  
MARIE CHODA
Keyword(s):  
Finite Group ◽  
Crossed Product ◽  
View Point ◽  
Jones Index ◽  
Outer Automorphisms ◽  
Outer Action ◽  
A Finite Group

Based on the fact that, for a subfactor N of a II1factor M, the first nontrivial Jones index is two and then M is decomposed as the crossed product of N by an outer action of ℤ2, we study pairs {N, uNu*} from the view-point of entropy for two subalgebras of M in connection with the entropy for automorphisms, where the inclusion of II1factors N ⊂ M is given with M being the crossed product of N by a finite group of outer automorphisms and u is a unitary in M.

Certain properties for crossed products by automorphisms with a certain non-simple tracial Rokhlin property

2012 ◽  
Vol 33 (5) ◽  
pp. 1391-1400 ◽  
Author(s):  
XIAOCHUN FANG ◽  
QINGZHAI FAN
Keyword(s):  
Finite Group ◽  
Crossed Product ◽  
Crossed Products ◽  
Infinite Dimensional ◽  
Crossed Product Algebra ◽  
A Finite Group ◽  
Product Algebra ◽  
Tracial Rokhlin Property

AbstractLet $\Omega $ be a class of unital $C^*$-algebras. Then any simple unital $C^*$-algebra $A\in \mathrm {TA}(\mathrm {TA}\Omega )$ is a $\mathrm {TA}\Omega $ algebra. Let $A\in \mathrm {TA}\Omega $ be an infinite-dimensional $\alpha $-simple unital $C^*$-algebra with the property SP. Suppose that $\alpha :G\to \mathrm {Aut}(A)$ is an action of a finite group $G$ on $A$ which has a certain non-simple tracial Rokhlin property. Then the crossed product algebra $C^*(G,A,\alpha )$ belongs to $\mathrm {TA}\Omega $.

scholarly journals THE DUAL STRUCTURE OF CROSSED PRODUCT -ALGEBRAS WITH FINITE GROUPS

2013 ◽  
Vol 88 (2) ◽  
pp. 243-249 ◽  
Author(s):  
FIRUZ KAMALOV
Keyword(s):  
Finite Group ◽  
Finite Groups ◽  
Orbit Space ◽  
Crossed Product ◽  
Irreducible Representations ◽  
Natural Action ◽  
Dual Structure ◽  
Projective Representations ◽  
A Finite Group ◽  
Sigma G

AbstractWe study the space of irreducible representations of a crossed product ${C}^{\ast } $-algebra ${\mathop{A\rtimes }\nolimits}_{\sigma } G$, where $G$ is a finite group. We construct a space $\widetilde {\Gamma } $ which consists of pairs of irreducible representations of $A$ and irreducible projective representations of subgroups of $G$. We show that there is a natural action of $G$ on $\widetilde {\Gamma } $ and that the orbit space $G\setminus \widetilde {\Gamma } $ corresponds bijectively to the dual of ${\mathop{A\rtimes }\nolimits}_{\sigma } G$.

scholarly journals C⁎-Basic Construction from the Conditional Expectation on the Drinfeld Double

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Qiaoling Xin ◽  
Lining Jiang ◽  
Tianqing Cao
Keyword(s):  
Finite Group ◽  
Conditional Expectation ◽  
Crossed Product ◽  
Drinfeld Double ◽  
Basic Construction ◽  
A Finite Group

Let D(G) be the Drinfeld double of a finite group G and D(G;H) be the crossed product of C(G) and CH, where H is a subgroup of G. Then the sets D(G) and D(G;H) can be made C⁎-algebras naturally. Considering the C⁎-basic construction C⁎〈D(G),e〉 from the conditional expectation E of D(G) onto D(G;H), one can construct a crossed product C⁎-algebra C(G/H×G)⋊CG, such that the C⁎-basic construction C⁎〈D(G),e〉 is C⁎-algebra isomorphic to C(G/H×G)⋊CG.

TILTED ALGEBRAS AND CROSSED PRODUCTS

2015 ◽  
Vol 58 (3) ◽  
pp. 559-571
Author(s):  
YANAN LIN ◽  
ZHENQIANG ZHOU
Keyword(s):  
Finite Group ◽  
Crossed Product ◽  
Crossed Products ◽  
Artin Algebra ◽  
Tilted Algebra ◽  
Tilted Algebras ◽  
Crossed Product Algebra ◽  
A Finite Group ◽  
Product Algebra

AbstractWe consider an artin algebra A and its crossed product algebra Aα#σG, where G is a finite group with its order invertible in A. Then, we prove that A is a tilted algebra if and only if so is Aα#σG.

scholarly journals On Galois Extension of Rings

1966 ◽  
Vol 27 (1) ◽  
pp. 43-49 ◽  
Author(s):  
Teruo Kanzaki
Keyword(s):  
Finite Group ◽  
Galois Extension ◽  
Crossed Product ◽  
Free Basis ◽  
A Finite Group ◽  
Factor Set

Let Λ be a ring and G a finite group of ring automorphisms of Λ. The totality of elements of Λ which are left invariant by G is a subring of Λ. We call it the G-fixed subring of Λ. Let be the crossed product of Λ and G with trivial factor set, i.e. {u0} is a Λ-free basis of Δ and , and let Γ be a subring of the G-fixed subring of Λ which has the same identity as Λ.

scholarly journals A CHARACTERIZATION OF SATURATED C*-ALGEBRAIC BUNDLES OVER FINITE GROUPS

2010 ◽  
Vol 88 (3) ◽  
pp. 363-383
Author(s):  
KAZUNORI KODAKA ◽  
TAMOTSU TERUYA
Keyword(s):  
Finite Group ◽  
Finite Type ◽  
Finite Groups ◽  
Conditional Expectation ◽  
Crossed Product ◽  
Sufficient Condition ◽  
Necessary And Sufficient Condition ◽  
A Finite Group ◽  
Necessary And Sufficient

AbstractLet A be a unital C*-algebra. Let (B,E) be a pair consisting of a unital C*-algebra B containing A as a C*-subalgebra with a unit that is also the unit of B, and a conditional expectation E from B onto A that is of index-finite type and of depth 2. Let B1 be the C*-basic construction induced by (B,E). In this paper, we shall show that any such pair (B,E) satisfying the conditions that A′∩B=ℂ1 and that A′∩B1 is commutative is constructed by a saturated C*-algebraic bundle over a finite group. Furthermore, we shall give a necessary and sufficient condition for B to be described as a twisted crossed product of A by its twisted action of a finite group under the condition that A′∩B1 is commutative.

On strongly associative group algebras of p-solvable groups

2015 ◽  
Vol 14 (06) ◽  
pp. 1550085 ◽  
Author(s):  
Jonas Gonçalves Lopes
Keyword(s):  
Finite Group ◽  
Solvable Group ◽  
Group Algebra ◽  
Modular Group ◽  
Solvable Groups ◽  
Crossed Product ◽  
Group Algebras ◽  
Characteristic P ◽  
Partial Action ◽  
A Finite Group

Given a partial action α of a group G on the group algebra FH, where H is a finite group and F is a field whose characteristic p divides the order of H, we investigate the associativity question of the partial crossed product FH *α G. If FH *α G is associative for any G and any α, then FH is called strongly associative. We characterize the strongly associative modular group algebras FH with H being a p-solvable group.

scholarly journals The Linear Span of Projections in AH Algebras and for Inclusions ofC*-Algebras

2013 ◽  
Vol 2013 ◽  
pp. 1-12
Author(s):  
Dinh Trung Hoa ◽  
Toan Minh Ho ◽  
Hiroyuki Osaka
Keyword(s):  
Fixed Point ◽  
Finite Group ◽  
Conditional Expectation ◽  
Linear Span ◽  
Crossed Product ◽  
Car Algebra ◽  
Crossed Product Algebra ◽  
Fixed Point Algebra ◽  
A Finite Group ◽  
Product Algebra

In the first part of this paper, we show that an AH algebraA=lim→(Ai,ϕi)has the LP property if and only if every element of the centre ofAibelongs to the closure of the linear span of projections inA. As a consequence, a diagonal AH-algebra has the LP property if it has small eigenvalue variation in the sense of Bratteli and Elliott. The second contribution of this paper is that for an inclusion of unitalC*-algebrasP⊂Awith a finite Watatani index, if a faithful conditional expectationE:A→Phas the Rokhlin property in the sense of Kodaka et al., thenPhas the LP property under the condition thatAhas the LP property. As an application, letAbe a simple unitalC*-algebra with the LP property,αan action of a finite groupGontoAut(A). Ifαhas the Rokhlin property in the sense of Izumi, then the fixed point algebraAGand the crossed product algebraA ⋊α Ghave the LP property. We also point out that there is a symmetry on the CAR algebra such that its fixed point algebra does not have the LP property.

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