Strong singularity of singular masas in II1 factors Academic Article uri icon


  • A singular masa A in a II 1 factor N is defined by the property that any unitary w N for which A = wAw* must lie in A. A strongly singular masa A is one that satisfies the inequality ||E A - E wAw* || ,2 ||w - E A (w)|| 2 for all unitaries w N, where E A is the conditional expectation of N onto A, and || || ,2 is defined for bounded maps : N N by sup{||(x)||2 : x N, ||x|| 1}. Strong singularity easily implies singularity, and the main result of this paper shows the reverse implication. 2007 University of Illinois.

published proceedings


author list (cited authors)

  • Sinclair, A. M., Smith, R. R., White, S. A., & Wiggins, A.

citation count

  • 8

complete list of authors

  • Sinclair, Allan M||Smith, Roger R||White, Stuart A||Wiggins, Alan

publication date

  • January 2007