The primitive ideal space of the C*-algebras of infinite graphs

The primitive ideal space of the C*-algebra of the affine semigroup of algebraic integers

We give a complete description of the primitive ideal space of the C*-algebra associated to the ring of integers R in a number field K as considered in a recent paper by Cuntz, Deninger and Laca.

The primitive ideals of some étale groupoid C*-algebras

Consider the Deaconu-Renault groupoid of an action of a finitely generated free abelian monoid by local homeomorphisms of a locally compact Hausdorff space. We catalogue the primitive ideals of the associated groupoid C*-algebra. For a special class of actions we describe the Jacobson topology.

Classification of real rank zero, purely infinite C*-algebras with at most four primitive ideals

Counterexamples to classification of purely infinite, nuclear, separable C*-algebras (in the ideal-related bootstrap class) and with primitive ideal space X using ideal-related K-theory occur for infinitely many finite primitive ideal spaces X, the smallest of which having four points. Ideal-related K-theory is known to be strongly complete for such C*-algebras if they have real rank zero and X has at most four points for all but two exceptional spaces: the pseudo-circle and the diamond space. In this article, we close these two remaining cases. We show that ideal-related K-theory is strongly …

Graph $C^\ast$-algebras with a $T_1$ primitive ideal space

We give necessary and sufficient conditions which a graph should satisfy in order for its associated $C^\ast$-algebra to have a $T_1$ primitive ideal space. We give a description of which one-point sets in such a primitive ideal space are open, and use this to prove that any purely infinite graph $C^\ast$-algebra with a $T_1$ (in particular Hausdorff) primitive ideal space, is a $c_0$-direct sum of Kirchberg algebras. Moreover, we show that graph $C^\ast$-algebras with a $T_1$ primitive ideal space canonically may be given the structure of a $C(\widetilde{\mathbb N})$-algebra, and that isomorp…

The prime spectrum and primitive ideal space of a graph C*-algebra

We describe primitive and prime ideals in the C*-algebra C*(E) of a graph E satisfying Condition (K), together with the topologies on each of these spaces. In particular, we find that primitive ideals correspond to the set of maximal tails disjoint union the set of finite-return vertices, and that prime ideals correspond to the set of clusters of maximal tails disjoint union the set of finite-return vertices.

The primitive ideals of the Cuntz-Krieger algebra of a row-finite higher-rank graph with no sources

We catalogue the primitive ideals of the Cuntz-Krieger algebra of a row-finite higher-rank graph with no sources. Each maximal tail in the vertex set has an abelian periodicity group of finite rank at most that of the graph; the primitive ideals in the Cuntz-Krieger algebra are indexed by pairs consisting of a maximal tail and a character of its periodicity group. The Cuntz-Krieger algebra is primitive if and only if the whole vertex set is a maximal tail and the graph is aperiodic.

$C^*(R_+)\rtimes R^\times$的本原理想空间

Primitive Ideal Space of $C^*(R_+)\rtimes R^\times$

该研究针对满足特定条件的整环，刻画了半群交叉积$C^*(R_+) \rtimes R^\times$的本原理想空间及其Jacobson拓扑，并以$R=\mathbb{Z}[\sqrt{-3}]$为主要示例。

The primitive ideal space of the partial-isometric crossed product of a system by a single automorphism

Let $(A,α)$ be a system consisting of a $C^*$-algebra $A$ and an automorphism $α$ of $A$. We describe the primitive ideal space of the partial-isometric crossed product $A\times_α^{\textrm{piso}}\mathbb{N}$ of the system by using its realization as a full corner of a classical crossed product and applying some results of Williams and Echterhoff.

The Primitive Ideal Space of Groupoid C*-Algebras for Groupoids with Abelian Isotropy

We study the topology of the primitive ideal space of groupoid C*-algebras for groupoids with abelian isotropy. Our results include the known results for action groupoids with abelian stabilizers. Furthermore, we obtain complete results when the isotropy map is continuous except for jump discontinuities, and also when $G$ is a unit space fixing extension of a proper groupoid by an abelian group bundle. We hope that our methods will be a springboard to further results of this type.

原始理想空间上的连续作用提升为$\mathrm{C}^{\ast}$-作用

Continuous actions on primitive ideal spaces lift to $\mathrm{C}^{\ast}$-actions

本文证明第二可数局部紧群在可分核C*-代数（满足吸收张量条件）原始理想空间上的连续作用可提升为代数上的作用，并应用于等变O2-稳定作用的分类。

$p$-adic整数乘法诱导作用的偏等距交叉积的原始理想空间

The primitive ideal space of the partial-isometric crossed product corresponding to an action induced by the multiplication on $p$-adic integers

本文研究了由$p$-adic整数乘法诱导出的半群作用下的偏等距交叉积的原始理想空间，并确定了其原始理想结构。

On Hong and Szymanski's description of the primitive-ideal space of a graph algebra

In 2004, Hong and Szymanski gave a complete description of the primitive-ideal space of the C*-algebra of a directed graph. This article details a slightly different approach, in the simpler context of row-finite graphs with no sources, obtaining an explicit description of the ideal lattice of a graph algebra.

Prime and Primitive Ideals of Ultragraph Leavitt Path Algebras

Let $\mathcal G$ be an ultragraph and let $K$ be a field. We describe prime and primitive ideals in the ultragraph Leavitt path algebra $L_K(\mathcal G)$. We identify the graded prime ideals in terms of downward directed sets and then we characterize the non-graded prime ideals. We show that the non-graded prime ideals of $L_K(\mathcal G)$ are always primitive.

Gluing Hilbert C*-modules over the primitive ideal space

We show that the gluing construction for Hilbert modules introduced by Raeburn in his computation of the Picard group of a continuous-trace C*-algebra (Trans. Amer. Math. Soc., 1981) can be applied to arbitrary C*-algebras, via an algebraic argument with the Haagerup tensor product. We put this result into the context of descent theory by identifying categories of gluing data for Hilbert modules over C*-algebras with categories of comodules over C*-coalgebras, giving a Hilbert-module version of a standard construction from algebraic geometry. As a consequence we show that if two C*-algebras ha…

半群 $\mathbb{N}^{2}$ 的自同构作用下偏等距交叉积的本原理想空间

The primitive ideal space of the partial-isometric crossed product by automorphic actions of the semigroup $\mathbb{N}^{2}$

本文研究半群 $\mathbb{N}^{2}$ 自同构作用产生的偏等距交叉积，借助其作为 $\mathbb{Z}^{2}$ 群交叉积全角的结构，完整刻画了该代数的本原理想空间。

关于自由群径向表示的原始理想空间

On the primitive ideal space of radial representations of free groups

本文研究自由群径向表示的原始理想空间，揭示其在C*-代数中的拓扑结构。

Primitive Ideals of Labelled Graph $C^*$-algebras

Given a directed graph $E$ and a labeling $\mathcal{L}$, one forms the labelled graph $C^*$-algebra by taking a weakly left--resolving labelled space $(E, \mathcal{L}, \mathcal{B})$ and considering a universal generating family of partial isometries and projections. In this paper we provide characterization for primitive ideals of labelled graph $C^*$-algebras.

Primitive ideals and K-theoretic approach to Bost-Connes systems

By KMS-classification theorem, the Dedekind zeta function is an invariant of Bost-Connes systems. In this paper, we show that it is in fact an invariant of Bost-Connes $C^*$-algebras. We examine second maximal primitive ideals of Bost-Connes $C^*$-algebras, and apply $K$-theory to some quotients.

本原理想空间的逆问题

The inverse problem for primitive ideal spaces

本文给出了可分离核 C*-代数本原理想空间的纯拓扑刻画，并利用伪开映射构造 Hilbert 双模和 Cuntz–Pimsner 代数，证明其本原理想空间同构于原空间，且与 C0(P) 具有 KK-等价性。

Primitive ideal space of Higher-rank graph $C^*$-algebras and decomposability

In this paper, we describe primitive ideal space of the $C^*$-algebra $C^*(Λ)$ associated to any locally convex row-finite $k$-graph $Λ$. To do this, we will apply the Farthing's desourcifying method on a recent result of Carlsen, Kang, Shotwell, and Sims. We also characterize certain maximal ideals of $C^*(Λ)$. Furthermore, we study the decomposability of $C^*(Λ)$. We apply the description of primitive ideals to show that if $I$ is a direct summand of $C^*(Λ)$, then it is gauge-invariant and isomorphic to a certain $k$-graph $C^*$-algebra. So, we may characterize decomposable higher-rank $C^*…

Meet Irreducible Ideals and Representations of Limit Algebras

In this paper we give a criterion for an ideal of a TAF algebra to be meet irreducible. We show that an ideal $J$ of $A$ is meet irreducile if and only if the C$^*$-envelope of the quotient $A/J$ is primitive. In that case, A/J admits a nest representation which extends to a *-representation of the C$^*$-envelope for $A/J.$ We also characterize the meet irreducible ideals as the kernels of nest representations; this settles the question of whether the n-primitive and meet irreducible ideals coincide.

AF-embeddability for Lie groups with $T_1$ primitive ideal spaces

We study simply connected Lie groups $G$ for which the hull-kernel topology of the primitive ideal space $\text{Prim}(G)$ of the group $C^*$-algebra $C^*(G)$ is $T_1$, that is, the finite subsets of $\text{Prim}(G)$ are closed. Thus, we prove that $C^*(G)$ is AF-embeddable. To this end, we show that if $G$ is solvable and its action on the centre of $[G, G]$ has at least one imaginary weight, then $\text{Prim}(G)$ has no nonempty quasi-compact open subsets. We prove in addition that connected locally compact groups with $T_1$ ideal spaces are strongly quasi-diagonal.

Primitive ideals and pure infiniteness of ultragraph $C^*$-algebras

Let $\mathcal{G}$ be an ultragraph and let $C^*(\mathcal{G})$ be the associated $C^*$-algebra introduced by Mark Tomforde. For any gauge invariant ideal $I_{(H,B)}$ of $C^*(\mathcal{G})$, we approach the quotient $C^*$-algebra $C^*(\mathcal{G})/I_{(H,B)}$ by the $C^*$-algebra of finite graphs and prove versions of gauge invariant and Cuntz-Krieger uniqueness theorems for it. We then describe primitive gauge invariant ideals and determine purely infinite ultragraph $C^*$-algebras (in the sense of Kirchberg-R$ø$rdam) via Fell bundles.

A class of C^*-algebras generalizing both graph algebras and homeomorphism C^*-algebras III, ideal structures

We investigate the ideal structures of the C^*-algebras arising from topological graphs. We give the complete description of ideals of such C^*-algebras which are invariant under the so-called gauge action, and give the condition on topological graphs so that all ideals are invariant under the gauge action. We get conditions for our C^*-algebras to be simple, prime or primitive. We completely determine the prime ideals, and show that most of them are primitive. Finally, we construct a discrete graph such that the associated C^*-algebra is prime but not primitive.

群胚C$^{*}$-代数中理想的迷向纤维

Isotropy fibers of ideals in groupoid C$^{*}$-algebras

该研究探讨局部紧平展群胚的群胚C$^*$-代数中理想与其迷向群的群C$^*$-代数理想族的决定关系，并应用该结论得到真理想与本原理想的包含关系、极大理想描述及一类分次群胚本原理想的分类结果。

On the ideals of ultragraph Leavitt path algebras

In this article, we provide an explicit description of a set of generators for any ideal of an ultragraph Leavitt path algebra. We provide several additional consequences of this description, including information about generating sets for graded ideals, the graded uniqueness and Cuntz-Krieger theorems, the semiprimeness, and the semiprimitivity of ultragraph Leavitt path algebras, a complete characterization of the prime and primitive ideals of an ultragraph Leavitt path algebra. We also show that every primitive ideal of an ultragraph Leavitt path algebra is exactly the annihilator of a Chen…

Crossed products whose primitive ideal spaces are generalized trivial $\widehat G$-bundles

We characterize when the primitive ideal space of a crossed product $\acg$ of a \cs-algebra $A$ by a locally compact abelian group $G$ is a $σ$-trivial $\ghat G$-space for the dual $\ghat G$-action. Specifically, we show that $\Prim(\acg)$ is $σ$-trivial if and only if the quasi-orbit space is Hausdorff, the map which assigns to each quasi-orbit $\w$ a certain subgroup $\ttg(α^\w)$ of the Connes spectrum of the system $(A_\w,G,α^\w)$ is continuous, and there is a generalized Green twisting map for $(A,G,α)$. Our proof requires a substantial generalization of a theorem of Olesen and Pedersen in…

The ideal structure of the C*-algebras of infinite graphs

We classify the gauge-invariant ideals in the C*-algebras of infinite directed graphs, and describe the quotients as graph algebras. We then use these results to identify the gauge-invariant primitive ideals in terms of the structural properties of the graph, and describe the K-theory of the C*-algebras of arbitrary infinite graphs.

The ideal structures of crossed products of Cuntz algebras by quasi-free actions of abelian groups

We completely determine the ideal structures of the crossed products of Cuntz algebras by quasi-free actions of abelian groups and give another proof of A. Kishimoto's result on the simplicity of such crossed products. We also give a necessary and sufficient condition that our algebras become primitive, and compute the Connes spectra and K-groups of our algebras.

Purely infinite C*-algebras of real rank zero

We show that a separable purely infinite C*-algebra is of real rank zero if and only if its primitive ideal space has a basis consisting of compact-open sets and the natural map K_0(I) -> K_0(I/J) is surjective for all closed two-sided ideals J contained in I in the C*-algebra. It follows in particular that if A is any separable C*-algebra, then A tensor O_2 is of real rank zero if and only if the primitive ideal space of A has a basis of compact-open sets, which again happens if and only if A tensor O_2 has the ideal property, also known as property (IP).

Centers of $C^*$-algebras rich in modular ideals

We provide, in the spirit of a 1968 paper of C. Delaroche, new conditions under which a $C^*$-algebra has a nonzero center.We also present an example of a (separable) AF algebra with center $\{0\}$ but whose all the primitive ideals are modular, thus answering a question from that paper of Delaroche.

Ideals in Operator Space Projective Tensor Product of $C^*$-algebras

For $C^*$-algebras $A$ and $B$, we prove the slice map conjecture for ideals in the operator space projective tensor product $A \hat\otimes B$. As an application, a characterization of prime ideals in the Banach $\ast$-algebra $A\hat\otimes B$ is obtained. Further, we study the primitive ideals, modular ideals and the maximal modular ideals of $A\hat\otimes B$. It is also shown that the Banach $\ast$-algebra $A\hat\otimes B$ possesses Wiener property; and that, for a subhomogenous $C^*$-algebra $A$, $A\hat\otimes B$ is symmetric.

The Theory of Prime Ideals of Leavitt Path Algebras over Arbitrary Graphs

Given an arbitrary graph E and a field K, the prime ideals as well as the primitive ideals of the Leavitt path algebra L_K(E) are completely described in terms of their generators. The stratification of the prime spectrum of L_K(E) is indicated with information on its individual stratum. Necessary and sufficient conditions are given on the graph E under which every prime ideal of L_K(E) is primitive. Leavitt path algebras of Krull dimension zero are characterized and those with various prescribed Krull dimension are constructed. The minimal prime ideals of L_K(E) are are described in terms of …

Classification of tight $C^{*}$-algebras over the one-point compactification of $\mathbb{N}$

We prove a strong classification result for a certain class of $C^{*}$-algebras with primitive ideal space $\widetilde{\mathbb{N}}$, where $\widetilde{\mathbb{N}}$ is the one-point compactification of $\mathbb{N}$. This class contains the class of graph $C^{*}$-algebras with primitive ideal space $\widetilde{\mathbb{N}}$. Along the way, we prove a universal coefficient theorem with ideal-related $K$-theory for $C^{*}$-algebras over $\widetilde{\mathbb{N}}$ whose $\infty$ fiber has torsion-free $K$-theory.

Ideals of etale groupoid algebras and Exel's Effros-Hahn conjecture

We extend to arbitrary commutative base rings a recent result of Demeneghi that every ideal of an ample groupoid algebra over a field is an intersection of kernels of induced representations from isotropy groups, with a much shorter proof, by using the author's Disintegration Theorem for groupoid representations. We also prove that every primitive ideal is the kernel of an induced representation from an isotropy group; however, we are unable to show, in general, that it is the kernel of an irreducible induced representation. If each isotropy group is finite (e.g., if the groupoid is principal)…

The topology of ideals in some triangular AF algebras

A set of meet-irreducible ideals is described for a class of maximal triangular almost finite algebras. This set forms a topological space under the hull-kernel closure, and there is a one-to-one correspondence between closed sets in this space and ideals in the AF algebra. Some connections with nest representations and nest-primitive ideals are also described.

A survey on the interplay between arithmetic mean ideals, traces, lattices of operator ideals, and an infinite Schur-Horn majorization theorem

The work of Dykema, Figiel, Weiss, and Wodzicki on the structure of commutators showed that arithmetic means play an important role in the study of operator ideals, and we explored their role in a multipaper project which we survey in this article. We start by presenting the notions of arithmetic mean ideals and arithmetic mean at infinity ideals. Then we explore their connections with commutator spaces, traces, elementary operators, lattice and sublattice structure of ideals, arithmetic mean ideal cancellation properties of first and second order, and softness properties - a term that we intr…

Reduction of filtered K-theory and a characterization of Cuntz-Krieger algebras

We show that filtered K-theory is equivalent to a substantially smaller invariant for all real-rank-zero C*-algebras with certain primitive ideal spaces -- including the infinitely many so-called accordion spaces for which filtered K-theory is known to be a complete invariant. As a consequence, we give a characterization of purely infinite Cuntz-Krieger algebras whose primitive ideal space is an accordion space.

真无限C*-代数中的李理想

Lie ideals in properly infinite C*-algebras

该研究证明含单位元的真无限C*-代数中李理想与唯一双边理想交换子等价，得到实秩零无特征标C*-代数的类似结果，并应用于von Neumann代数解决了相关公开问题。

Superposition, transition probabilities and primitive observables in infinite quantum systems

The concepts of superposition and of transition probability, familiar from pure states in quantum physics, are extended to locally normal states on funnels of type I$_\infty$ factors. Such funnels are used in the description of infinite systems, appearing for example in quantum field theory or in quantum statistical mechanics; their respective constituents are interpreted as algebras of observables localized in an increasing family of nested spacetime regions. Given a generic reference state (expectation functional) on a funnel, e.g, a ground state or a thermal equilibrium state, it is shown t…

Hopf algebras of primitive Lie pseudogroups and Hopf cyclic cohomology

We associate to each infinite primitive Lie pseudogroup a Hopf algebra of `transverse symmetries', by refining a procedure due to Connes and the first author in the case of the general pseudogroup. The affiliated Hopf algebra can be viewed as a `quantum group' counterpart of the infinite-dimensional primitive Lie algebra of the pseudogroup. It is first constructed via its action on the étale groupoid associated to the pseudogroup, and then realized as a bicrossed product of a universal enveloping algebra by a Hopf algebra of regular functions on a formal group. The bicrossed product structure …