6 papers
The Spectral Scale and the k-Numerical Range
Charles A. Akemann, Joel Anderson
Suppose that c is a linear operator acting on an n-dimensional complex Hilbert Space H, and let tau denote the normalized trace on B(H). Set b_1 = (c+c*)/2 and b_2 = (c-c*)/2i, and…
Automatic convexity
Charles A. Akemann, Nik Weaver
In many cases the convexity of the image of a linear map with range is is automatic because of the facial structure of the domain of the map. We develop a four step procedure…
Geometric characterizations of some classes of operators in C*-algebras and von Neumann algebras
Charles Akemann, Nik Weaver
We present geometric characterizations of the partial isometries, unitaries, and invertible operators in C*-algebras and von Neumann algebras.
A geometric spectral theory for n-tuples of self-adjoint operators in a finite von Neumann algebra: II
Charles A. Akemann, Joel Anderson
Given an n-tuple {b_1, ..., b_n} of self-adjoint operators in a finite von Neumann algebra M and a faithful, normal tracial state tau on M, we define a map Psi from M to R^{n+1} by…
Locally Minimal Projections
Charles A. Akemann, Joel Anderson
Given an n-tuple {a_1, ..., a_n} of self-adjoint operators on an infinite dimensional Hilbert space H and a positive integer k, there exists a projection p of rank k such that, for…
Regularity of projections revisited
Charles A. Akemann, Soren Eilers
The concept of regularity in the meta-topological setting of projections in the double dual of a C*-algebra addresses the interrelations of a projection p with its closure, for ins…