The Kadison-Singer Problem

September 25 to September 29, 2006

at the

American Institute of Mathematics, Palo Alto, California

organized by

Pete Casazza, Richard Kadison, and David Larson

Original Announcement

This workshop will be devoted to the Kadison-Singer Problem and its relationship to various areas of research in mathematics and engineering.

The 1959 Kadison-Singer Problem in C*-algebras has defied the best efforts of some of the most talented mathematicians of our time. Recently it was shown that this problem is equivalent to fundamental unsolved problems in a dozen areas of research in Pure Mathematics, Applied Mathematics and Engineering, including: operator theory, Banach space theory, harmonic analysis, and signal processing.

The specific purpose of this workshop is to bring together some of the top minds in the various areas of research impacted by the Kadison-Singer Problem to see if we can resolve the problem. For more realistic goals, we expect:

  1. The participants to release partial results they have on the problem;
  2. To formulate related problems that might be more tractable than the full-scope problem, and could potentially lead to the eventual solution of the problem;
  3. To map out possible "paths" that could lead to the solution - especially interactive paths between two or more research areas; and
  4. To establish long term relationships between people from the diverse areas of research impacted by Kadison-Singer which will lead to interactive research in the future.
We anticipate having only one talk each day presenting an introduction to one area impacted by the Kadison-Singer Problem. These talks will form an introduction to the workshop's activities for that day.

Material from the workshop

A list of participants.

The workshop schedule.

A report on the workshop activities.


The following papers contain an introduction to various aspects of the Kadison-Singer problem.

Kadison-Singer from mathematical physics: an introduction by Palle Jorgensen

State extensions and the Kadison-Singer problem by Akemann and Paulsen.

Paving and the Kadison-Singer problem, by Casazza, Paulsen, and Weiss.

Frames and the Kadison-Singer problem, by Casazza, Kutyniok, Larsen, and Speegle.

Open problems

Below one can find lists of problems around Kadison-Singer that might be more approachable than the entire conjecture.

Problems on paving and the Kadison-Singer problem

Problems on frames and the Kadison-Singer problem

Recent observations

These papers contain recent results that will be of interest to those working on problems related to Kadison-Singer.

The paving property for uniformly bounded matrices, by Tropp

The paving conjecture is equivalent to the paving conjecture for triangular matrices by Casazza and Tremain

A decomposition theorem for frames and the Feichtinger conjecture, by Casazza, Kutyniok, Speegle, and Tremain

Projections and the Kadison-Singer problem, by Casazza, Edidin, Kalra, and Paulsen