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Full-Text Articles in Social and Behavioral Sciences
Cartan Subalgebras In C*-Algebras Of Hausdorff Étale Groupoids, Jonathan H. Brown, Gabriel Nagy, Sarah Reznikoff, Aidan Sims, Dana P. Williams
Cartan Subalgebras In C*-Algebras Of Hausdorff Étale Groupoids, Jonathan H. Brown, Gabriel Nagy, Sarah Reznikoff, Aidan Sims, Dana P. Williams
Faculty of Engineering and Information Sciences - Papers: Part A
The reduced C*-algebra of the interior of the isotropy in any Hausdorff étale groupoid G embeds as a C*-subalgebra M of the reduced C*-algebra of G. We prove that the set of pure states of M with unique extension is dense, and deduce that any representation of the reduced C*-algebra of G that is injective on M is faithful. We prove that there is a conditional expectation from the reduced C*-algebra of G onto M if and only if the interior of the isotropy in G is closed. Using this, we prove that when the interior of the isotropy is …
Breakaway Oxidation Behaviour Of Ferritic Stainless Steels At 1150 °C In Humid Air, Xiawei Cheng, Zhengyi Jiang, Brian J. Monaghan, Dongbin Wei, Raymond Longbottom, Jingwei Zhao, Jianguo Peng, Ming Luo, Li Ma, Suzhen Luo, Laizhu Jiang
Breakaway Oxidation Behaviour Of Ferritic Stainless Steels At 1150 °C In Humid Air, Xiawei Cheng, Zhengyi Jiang, Brian J. Monaghan, Dongbin Wei, Raymond Longbottom, Jingwei Zhao, Jianguo Peng, Ming Luo, Li Ma, Suzhen Luo, Laizhu Jiang
Faculty of Engineering and Information Sciences - Papers: Part A
The breakaway oxidation behaviour of ferritic stainless steels 430, 443 and 445 has been investigatedat 1150◦C in humid air. The oxidation kinetics exhibited significant differences among the three ferriticstainless steels. A uniform and steady growing oxide scale was developed on the 430 steel with an evensteel/oxide interface. Local breakdown of the initially protective oxide scale occurred and oxide noduleswere developed on the 443 and 445 stainless steels, resulting in irregular and rough steel/oxide inter-faces. The breakaway oxidation behaviour was significantly influenced by the microstructure and thecomposition of the oxide scale. The Mn-Cr spinel oxide formed on top of the Cr2O3scale …
Microstructure And Micro-Texture Evolution During The Dynamic Recrystallisation Of A Ni-30fe-Nb-C Model Alloy, Parvez Mannan, Ahmed A. Saleh, Azdiar A. Gazder, Gilberto Casillas, Elena V. Pereloma
Microstructure And Micro-Texture Evolution During The Dynamic Recrystallisation Of A Ni-30fe-Nb-C Model Alloy, Parvez Mannan, Ahmed A. Saleh, Azdiar A. Gazder, Gilberto Casillas, Elena V. Pereloma
Faculty of Engineering and Information Sciences - Papers: Part A
The evolution of microstructure and micro-texture during discontinuous dynamic recrystallisation of an austenitic Ni-30Fe-Nb-C model alloy subjected to interrupted plane strain compression at strains (ε) of 0.23, 0.35, 0.68, 0.85 and 1.2 was investigated using electron backscattering diffraction and transmission electron microscopy. Throughout the strain range, the majority of dynamic recrystallisation events comprised nucleation in necklace-like arrangements located at and along grain boundaries via bulging. At ε ≥ 0.68, discrete nucleation events were also observed within grain interiors. Grain growth during dynamic recrystallisation is characteristic of strain induced boundary migration. The initial texture comprised Cube-RD ({013}〈100〉), Cube-ND ({001}〈310〉) and Cube …
The Nuclear Dimension Of Graph C*-Algebras, Efren Ruiz, Aidan Sims, Mark Tomforde
The Nuclear Dimension Of Graph C*-Algebras, Efren Ruiz, Aidan Sims, Mark Tomforde
Faculty of Engineering and Information Sciences - Papers: Part A
Consider a graph C⁎C⁎-algebra C⁎(E)C⁎(E) with a purely infinite ideal I (possibly all of C⁎(E)C⁎(E)) such that I has only finitely many ideals and C⁎(E)/IC⁎(E)/I is approximately finite dimensional. We prove that the nuclear dimension of C⁎(E)C⁎(E) is 1. If I has infinitely many ideals, then the nuclear dimension of C⁎(E)C⁎(E) is either 1 or 2.
3d Bridge Microdosimeter: Charge Collection Study And Application To Rbe Studies In 12C Radiation Therapy, Linh T. Tran, Dale A. Prokopovich, Susanna Guatelli, Marco Petasecca, Michael L. F Lerch, Mark I. Reinhard, Anatoly B. Rosenfeld
3d Bridge Microdosimeter: Charge Collection Study And Application To Rbe Studies In 12C Radiation Therapy, Linh T. Tran, Dale A. Prokopovich, Susanna Guatelli, Marco Petasecca, Michael L. F Lerch, Mark I. Reinhard, Anatoly B. Rosenfeld
Faculty of Engineering and Information Sciences - Papers: Part A
Radiotherapy using heavy ion beam such as Carbon-ion has the advantage for the treatment of deep-seated tumour over conventional radiotherapy with X-rays due to an enhanced dose deposition in the Bragg peak (BP) at the end of the ion range. The highest dose can be deposited in the tumour with much lower doses to the surrounding healthy tissue. The Relative Biological Effectiveness (RBE) of a carbon-ion radiotherapy beam greatly depends on a depth of the target volume in the body and the nuclear fragmentation process that increases close to the BP or spread out BP (SOBP) as well as neutrons. …
Boundary C^{2,\Alpha} Estimates For Monge-Ampere Type Equations, Yong Huang, Feida Jiang, Jiakun Liu
Boundary C^{2,\Alpha} Estimates For Monge-Ampere Type Equations, Yong Huang, Feida Jiang, Jiakun Liu
Faculty of Engineering and Information Sciences - Papers: Part A
In this paper, we obtain global second derivative estimates for solutions of the Dirichlet problem of certain Monge-Ampère type equations under some structural conditions, while the inhomogeneous term is only assumed to be Hölder continuous and bounded away from zero and infinity. These estimates correspond to those for the standard Monge-Ampère equation obtained by Trudinger and Wang (2008) and by Savin (2013), and have natural applications in optimal transportation and prescribed Jacobian equations.
High Temperature Dislocation Structure And Nbc Precipitation In Three Ni-Fe-Nb-C Model Alloys, Andrii Kostryzhev, Parvez Mannan, Olexandra Marenych
High Temperature Dislocation Structure And Nbc Precipitation In Three Ni-Fe-Nb-C Model Alloys, Andrii Kostryzhev, Parvez Mannan, Olexandra Marenych
Faculty of Engineering and Information Sciences - Papers: Part A
In this original work, the dislocation structure and NbC precipitation were investigated in three Ni-based alloys (70Ni-Fe-0.331Nb-0.040C, 70Ni-Fe-0.851Nb-0.114C and 70Ni-Fe-1.420Nb-0.157C, wt%) thermomechanically processed in the temperature range of 1250-1075 °C. The dislocation structure inhomogeneity (dislocation networks and cell walls), which we observed in the middle and high Nb+C alloys, resulted from the dislocation pile-ups in the vicinity of >200 nm NbC particles. The dislocation density around >200 nm particles exceeded the average values by 5-7 times, and that in the cell walls might exceed the average values by 10 times. Twins and stacking faults were observed in all alloys after …
Purely Infinite C*-Algebras Associated To Etale Groupoids, Jonathon Brown, Les Clark, Adam Sierakowski
Purely Infinite C*-Algebras Associated To Etale Groupoids, Jonathon Brown, Les Clark, Adam Sierakowski
Faculty of Engineering and Information Sciences - Papers: Part A
No abstract provided.
Kms States On The C-Algebras Of Reducible Graphs, Astrid An Huef, Marcelo Laca, Iain Raeburn, Aidan Sims
Kms States On The C-Algebras Of Reducible Graphs, Astrid An Huef, Marcelo Laca, Iain Raeburn, Aidan Sims
Faculty of Engineering and Information Sciences - Papers: Part A
We consider the dynamics on the C-algebras of finite graphs obtained by lifting the gauge action to an action of the real line. Enomoto, Fujii and Watatani [KMS states for gauge action on OA. Math. Japon. 29 (1984), 607-619] proved that if the vertex matrix of the graph is irreducible, then the dynamics on the graph algebra admits a single Kubo-Martin-Schwinger (KMS) state. We have previously studied the dynamics on the Toeplitz algebra, and explicitly described a finite-dimensional simplex of KMS states for inverse temperatures above a critical value. Here we study the KMS states for graphs with reducible vertex …
Characterisation Of Coke Packed Beds After Liquid Slag Flow At 1 500°C By Image Analysis, Hazem Labib George, Raymond Longbottom, Sheng Chew, David Pinson, Brian Monaghan
Characterisation Of Coke Packed Beds After Liquid Slag Flow At 1 500°C By Image Analysis, Hazem Labib George, Raymond Longbottom, Sheng Chew, David Pinson, Brian Monaghan
Faculty of Engineering and Information Sciences - Papers: Part A
The flow of slag in the lower zone of the ironmaking blast furnace was experimentally simulated by adding slag to a high temperature laboratory scale coke packed bed. The flow of slag through packed beds of coke with packing densities varying from 50% to 65% was examined at 1 500°C. Since the liquid flow through a packed bed depends on packing properties such as particle size, particle shape, pore size and pore neck size, it was necessary to characterise these properties of the beds. In this work, image analysis of successive sections of the tested beds was utilised to characterise …
Kms States On C*-Algebras Associated To Higher-Rank Graphs, Astrid An Huef, Marcelo Laca, Iain Raeburn, Aidan Sims
Kms States On C*-Algebras Associated To Higher-Rank Graphs, Astrid An Huef, Marcelo Laca, Iain Raeburn, Aidan Sims
Faculty of Engineering and Information Sciences - Papers: Part A
Consider a higher rank graph of rank k. Both the Cuntz-Krieger algebra and Toeplitz-Cuntz-Krieger algebra of the graph carry natural gauge actions of the torus Tk, and restricting these guage actions to one parameter subgroups of Tk gives dynamical systems involving actions of the real line. We study the KMS states of these dynamical systems. We find that for large inverse temperatures B, the simplex of KMS B states of the Toeplitz-Cuntz-Krieger algebra has dimension d one less than the number of vertices in the graph. We also show that there is a preferred dynamics for which there is a …
Group Actions On Labeled Graphs And Their C*-Algebras, Teresa Bates, David Pask, Paulette Willis
Group Actions On Labeled Graphs And Their C*-Algebras, Teresa Bates, David Pask, Paulette Willis
Faculty of Engineering and Information Sciences - Papers: Part A
We introduce the notion of the action of a group on a labeled graph and the quotient object, also a labeled graph. We define a skew product labeled graph and use it to prove a version of the Gross–Tucker theorem for labeled graphs. We then apply these results to the C -algebra associated to a labeled graph and provide some applications in non-Abelian duality.
Zappa-Szep Products Of Semigroups And Their C*-Algebras, Nathan D. Brownlowe, Jacqueline Ramagge, David I. Robertson, Michael F. Whittaker
Zappa-Szep Products Of Semigroups And Their C*-Algebras, Nathan D. Brownlowe, Jacqueline Ramagge, David I. Robertson, Michael F. Whittaker
Faculty of Engineering and Information Sciences - Papers: Part A
Zappa-Szep products of semigroups provide a rich class of examples of semigroups that include the self-similar group actions of Nekrashevych. We use Li's construction of semigroups C*-algebras to associate a C*-algebra to Zappa-Szep products and give an explicit presentation of the algebra. We then define a quotient C*-algebra that generalises the Cuntz-Pimsner algebras for self-similar actions. We indicate how knowne examples, previously viewed as distinct classes, fit into our unifying framework. We specifically discuss the Baumslag-Solitar groups, the binary adding machine, the semigroup NXNx, and the ax+b semigroup ZXZx.
Twisted C-Algebras Associated To Finitely Aligned Higher-Rank Graphs, Aidan Sims, Benjamin Whitehead, Michael Whittaker
Twisted C-Algebras Associated To Finitely Aligned Higher-Rank Graphs, Aidan Sims, Benjamin Whitehead, Michael Whittaker
Faculty of Engineering and Information Sciences - Papers: Part A
We introduce twisted relative Cuntz-Krieger algebras associated to finitely aligned higher-rank graphs and give a comprehensive treatment of their fundamental structural properties. We establish versions of the usual uniqueness theorems and the classification of gauge-invariant ideals. We show that all twisted relative Cuntz- Krieger algebras associated to finitely aligned higher-rank graphs are nuclear and satisfy the UCT, and that for twists that lift to real-valued cocycles, the K-theory of a twisted relative Cuntz-Krieger algebra is independent of the twist. In the final section, we identify a sufficient condition for simplicity of twisted Cuntz-Krieger algebras associated to higher-rank graphs which are …
An Elementary Approach To C*-Algebras Associated To Topological Graphs, Hui Li, David Pask, Aidan Sims
An Elementary Approach To C*-Algebras Associated To Topological Graphs, Hui Li, David Pask, Aidan Sims
Faculty of Engineering and Information Sciences - Papers: Part A
We develop notions of a representation of a toopological grapph E and of a covariant representation of a topological graph E which do onot require the machinery of C* -correspondences and Cuntz-Pimsner alegebars. We show that the C* -algebra generated by a universal representation of E is isomorphic to the Toeplitz algebra of Katsura's topological-graph bimodule, and that the C* palgebra generated by a universal covariant representation of E is isomorphic to Katsura's topological graph C* -algebra. We exhibit our resluts by constructing the isomorphism between the C* -algebra of the row-finite directed graph E with no sources and the …
On The K-Theory Of Twisted Higher-Rank-Graph C*-Algebras, Alex Kumjian, David Pask, Aidan Sims
On The K-Theory Of Twisted Higher-Rank-Graph C*-Algebras, Alex Kumjian, David Pask, Aidan Sims
Faculty of Engineering and Information Sciences - Papers: Part A
We investigate the K-theory of twisted higher-rank-graph algebras by adapting parts of Elliott's computation of the K-theory of the rotation algebras. We show that each 2-cocycle on a higher-rank graph taking values in an abelian group determines a continuous bundle of twisted higher-rank graph algebras over the dual group. We use this to show that for a circle-valued 2-cocycle on a higher-rank graph obtained by exponentiating a real-valued cocycle, the K-theory of the twisted higher-rank graph algebra coincides with that of the untwisted one.
Catalytic Role Of Ge In Highly Reversible Geo2/Ge/C Nanocomposite Anode Material For Lithium Batteries, Kuok Hau Seng, Mi-Hee Park, Zai Ping Guo, Hua-Kun Liu, Jaephil Cho
Catalytic Role Of Ge In Highly Reversible Geo2/Ge/C Nanocomposite Anode Material For Lithium Batteries, Kuok Hau Seng, Mi-Hee Park, Zai Ping Guo, Hua-Kun Liu, Jaephil Cho
Faculty of Engineering and Information Sciences - Papers: Part A
GeO2/Ge/C anode material synthesized using a simple method involving simultaneous carbon coating and reduction by acetylene gas is composed of nanosized GeO2/Ge particles coated by a thin layer of carbon, which is also interconnected between neighboring particles to form clusters of up to 30 μm. The GeO2/Ge/C composite shows a high capacity of up to 1860 mAh/g and 1680 mAh/g at 1 C (2.1 A/g) and 10 C rates, respectively. This good electrochemical performance is related to the fact that the elemental germanium nanoparticles present in the composite increases the reversibility of the conversion reaction of GeO2. These factors have …
Kms States On The C*-Algebras Of Finite Graphs, Astrid An Huef, Marcelo Laca, Iain F. Raeburn, Aidan D. Sims
Kms States On The C*-Algebras Of Finite Graphs, Astrid An Huef, Marcelo Laca, Iain F. Raeburn, Aidan D. Sims
Faculty of Engineering and Information Sciences - Papers: Part A
We consider a finite directed graph E, and the gauge action on its Toeplitz-Cuntz-Krieger algebra, viewed as an action of R. For inverse temperatures larger than a critical value βc, we give an explicit construction of all the KMSβ states. If the graph is strongly connected, then there is a unique KMSβc state, and this state factors through the quotient map onto C*(E). Our approach is direct and relatively elementary.
A Unique Sandwich-Structured C/Ge/Graphene Nanocomposite As An Anode Material For High Power Lithium Ion Batteries, Dan Li, Kuok H. Seng, Dongqi Shi, Zhixin Chen, Hua-Kun Liu, Zaiping Guo
A Unique Sandwich-Structured C/Ge/Graphene Nanocomposite As An Anode Material For High Power Lithium Ion Batteries, Dan Li, Kuok H. Seng, Dongqi Shi, Zhixin Chen, Hua-Kun Liu, Zaiping Guo
Faculty of Engineering and Information Sciences - Papers: Part A
A unique sandwich-structured C/Ge/graphene composite with germanium nanoparticles trapped between graphene sheets is prepared by a microwave-assisted solvothermal reaction followed by carbon coating and thermal reduction. The graphene sheets are found to be effective in hindering the growth and aggregation of GeO2 nanoparticles. More importantly, the graphene sheets, coupled with the carbon coating, can buffer the volume changes of germanium in electrochemical lithium reactions. The unique sandwich structure features a highly conductive network of carbon, which can improve both the conductivity and the structural stability of the electrode material, and exemplifies a promising strategy for the development of new high …
Remarks On Some Fundamental Results About Higher-Rank Graphs And Their C*-Algebras, Robert Hazlewood, Iain Raeburn, Aidan Sims, Samuel B. G Webster
Remarks On Some Fundamental Results About Higher-Rank Graphs And Their C*-Algebras, Robert Hazlewood, Iain Raeburn, Aidan Sims, Samuel B. G Webster
Faculty of Engineering and Information Sciences - Papers: Part A
Results of Fowler and Sims show that every k-graph is completely determined by its k-coloured skeleton and collection of commuting squares. Here we give an explicit description of the k-graph associated with a given skeleton and collection of squares and show that two k-graphs are isomorphic if and only if there is an isomorphism of their skeletons which preserves commuting squares. We use this to prove directly that each k-graph. is isomorphic to the quotient of the path category of its skeleton by the equivalence relation determined by the commuting squares, and show that this extends to a homeomorphism of …
Realising The C*-Algebra Of A Higher-Rank Graph As An Exel's Crossed Product, Nathan Brownlowe
Realising The C*-Algebra Of A Higher-Rank Graph As An Exel's Crossed Product, Nathan Brownlowe
Faculty of Engineering and Information Sciences - Papers: Part A
We use the boundary-path space of a finitely-aligned k-graph Lambda to construct a compactly-aligned product system X, and we show that the graph algebra C*(Lambda) is isomorphic to the Cuntz-Nica-Pimsner algebra NO(X). In this setting, we introduce the notion of a crossed product by a semigroup of partial endomorphisms and partially-defined transfer operators by defining it to be NO(X). We then compare this crossed product with other definitions in the literature.
Synthesis And Electrochemical Properties Of Sn-Sno2/C Nanocomposite, Chuanqi Feng, Meiyu Dan, Chaofeng Zhang, Zaiping Guo, Shiquan Wang, R Zeng
Synthesis And Electrochemical Properties Of Sn-Sno2/C Nanocomposite, Chuanqi Feng, Meiyu Dan, Chaofeng Zhang, Zaiping Guo, Shiquan Wang, R Zeng
Faculty of Engineering and Information Sciences - Papers: Part A
A Sn-Sn02/C nanocomposite was synthesized using the electrospinning method. Thermal analysis was used to determine the content range of Sn and Sn02 in the composite. The composite was characterized by X-ray diffraction, and the particle size and shape in the Sn-SnOiC composite were determined by scanning and transmission electron microscopy. The results show that the Sn-Sn02/C composite takes on a nanofiber morphology, with the diameters of the nanofibers distributed from 50 to 200 nm. The electrOChemical properties of the Sn-SnOiC composite were also investigated. The Sn-SnOiC composite as an electrode material has both higher reversible capacity (887 mAh· g-I). and …
Purely Infinite C-Algebras Arising From Crossed Products, Mikael Rordam, Adam Sierakowski
Purely Infinite C-Algebras Arising From Crossed Products, Mikael Rordam, Adam Sierakowski
Faculty of Engineering and Information Sciences - Papers: Part A
We study conditions that will ensure that a crossed product of a C-algebra by a discrete exact group is purely infinite (simple or non-simple). We are particularly interested in the case of a discrete non-amenable exact group acting on a commutative C-algebra, where our sufficient conditions can be phrased in terms of paradoxicality of subsets of the spectrum of the abelian C-algebra. As an application of our results we show that every discrete countable non-amenable exact group admits a free amenable minimal action on the Cantor set such that the corresponding crossed product C-algebra is a Kirchberg algebra in the …
Families Of Type Iii Kms States On A Class Of C-Algebras Containing On And Qn, A L. Carey, J Phillips, I F. Putnam, A Rennie
Families Of Type Iii Kms States On A Class Of C-Algebras Containing On And Qn, A L. Carey, J Phillips, I F. Putnam, A Rennie
Faculty of Engineering and Information Sciences - Papers: Part A
We construct a family of purely infinite C¤-algebras, Q¸ for ¸ 2 (0, 1) that are classified by their K-groups. There is an action of the circle T with a unique KMS state à on each Q¸. For ¸ = 1/n, Q1/n »= On, with its usual T action and KMS state. For ¸ = p/q, rational in lowest terms, Q¸ »= On (n = q − p + 1) with UHF fixed point algebra of type (pq)1. For any n > 1, Q¸ »= On for infinitely many ¸ with distinct KMS states and UHF fixed-point algebras. For any ¸ …
Purely Infinite Simple C*-Algebras Associated To Integer Dilation Matrices, Ruy Exel, Astrid An Huef, Iain Raeburn
Purely Infinite Simple C*-Algebras Associated To Integer Dilation Matrices, Ruy Exel, Astrid An Huef, Iain Raeburn
Faculty of Engineering and Information Sciences - Papers: Part A
Given an n×n integer matrix A whose eigenvalues are strictly greater than 1 in absolute value, let σA be the transformation of the n-torus Tn = Rn/Zn defined by σA(e2πix) = e2πiAx for x ∈ Rn. We study the associated crossed-product C∗-algebra, which is defined using a certain transfer operator for σA, proving it to be simple and purely infinite and computing its K-theory groups.
C*-Algebras Associated To C*-Correspondences And Applications To Mirror Quantum Spheres, David I. Robertson, Wojciech Szymanski
C*-Algebras Associated To C*-Correspondences And Applications To Mirror Quantum Spheres, David I. Robertson, Wojciech Szymanski
Faculty of Engineering and Information Sciences - Papers: Part A
The structure of the C*-algebras corresponding to even-dimensional mirror quantum spheres is investigated. It is shown that they are isomorphic to both Cuntz-Pimsner algebras of certain C*-correspondences and C*-algebras of certain labelled graphs. In order to achieve this, categories of labelled graphs and C*-correspondences are studied. A functor from labelled graphs to C*-correspondences is constructed, such that the corresponding associated C*-algebras are isomorphic. Furthermore, it is shown that C*-correspondences for the mirror quantum spheres arise via a general construction of restricted direct sum.
Semifinite Spectral Triples Associated With Graph C*-Algebras, Alan L. Carey, John Phillips, Adam Rennie
Semifinite Spectral Triples Associated With Graph C*-Algebras, Alan L. Carey, John Phillips, Adam Rennie
Faculty of Engineering and Information Sciences - Papers: Part A
We review the recent construction of semifinite spectral triples for graph C^*-algebras. These examples have inspired many other developments and we review some of these such as the relation between the semifinite index and the Kasparov product, examples of noncommutative manifolds, and an index theorem in twisted cyclic theory using a KMS state.
Properties Preserved Under Morita Equivalence Of C*-Algebras, Astrid An Huef, Iain Raeburn, Dana Williams
Properties Preserved Under Morita Equivalence Of C*-Algebras, Astrid An Huef, Iain Raeburn, Dana Williams
Faculty of Engineering and Information Sciences - Papers: Part A
We show that important structural properties of C*-algebras and the muliplicity numbers of representations are preserved under Morita equivalence.
Extension Problems And Non-Abelian Duality For C*-Algebras, Astrid An Huef, S Kaliszewski, Iain Raeburn
Extension Problems And Non-Abelian Duality For C*-Algebras, Astrid An Huef, S Kaliszewski, Iain Raeburn
Faculty of Engineering and Information Sciences - Papers: Part A
Suppose that H is a closed subgroup of a locally compact group G. We show that a unitary representation U of H is the restriction of a unitary representation of G if and only if a dual representation Û of a crossed product C*(G) (G/H) is regular in an appropriate sense. We then discuss the problem of deciding whether a given representation is regular; we believe that this problem will prove to be an interesting test question in non-Abelian duality for crossed products of C*-algebras.
Subquotients Of Hecke C*-Algebras, Nathan Brownlowe, Nadia Larsen, Ian Putnam, Iain Raeburn
Subquotients Of Hecke C*-Algebras, Nathan Brownlowe, Nadia Larsen, Ian Putnam, Iain Raeburn
Faculty of Engineering and Information Sciences - Papers: Part A
We realize the Hecke C*-algebra CQ of Bost and Connes as a direct limit of Hecke C*-algebras which are semigroup crossed products by NF, for F a finite set of primes. For each approximating Hecke C*-algebra we describe a composition series of ideals. In all cases there is a large type I ideal and a commutative quotient, and the intermediate subquotients are direct sums of simple C*-algebras. We can describe the simple summands as ordinary crossed products by actions of ZS for S a finite set of primes. …