# Heydar Radjavi

Telephone: (902) 494-3311

Office: 303

email: radjavi@mscs.dal.ca

## Current Research

Reducibility and
triangularizability of collections of operators

Homomorphisms of operator semigroups

Structure of operator semigroups satisfying given spectral conditions

Structure of operator bands
## Typical Publications

Sublinearity and other spectral conditions on a semigroup, submitted.
A finiteness lemma, Brauer's Theorem. and other irreducibility results
(with M. Radjabalipour), Communications in Algebra, to appear.
Reducible semigroups of idempotent operators (with L. Livshits, G.
MacDonald, and B. Mathes), J. Operator Theory 40(1998),35-69.
On permutability and submultiplicativity of spectral radius (with W.
Longstaff), Canadian J. Math.47(1995),1007-1022.
Toward a classification of maximal unicellular bands (with P. Fillmore, G.
MacDonald, and M. Radjabalipour), Semigroup Forum 49(1994), 195-215.
Approximation by products of positive operators (with M. Khalkhali, C.
Laurie, and B. Mathes), J. Operator Theory 29(1993), 237-247.
Jordan Analogs of the Burnside and Jacobson Density Theorems (with L.
Grunenfelder and M. Omladic), Pacific J. Math. 161(1993), 335-346.
Spectral conditions and reducibility of operator semigroups (with M.
Lambrou and W. Longstaff), Indiana Univ. Math. J. 41(1992), 449-464.
Simultaneous triangularization of collections of operators (with D.
Hadwin, E. Nordgren, M. Radjabalipour, and P. Rosenthal), Houston J. Math.
17(1991), 581-602.
## Scholarly Contributions

About 105 papers in refereed journals
Recently published book entitled Simultaneous Triangularization (with P.
Rosenthal) in the Springer Universitext Series, 2000.
Book entitled Invariant Subspaces (with P. Rosenthal) in the Ergebnisse
der Mathematic series.
Expository articles in Conference Proceedings.
Service as member of the Grant Selection Committee for the Natural
Sciences and Engineering Reseach Council of Canada, 1975-1978 and
1996-1999.
Service as editor-in-chief (with M. Edelstein) for the Canadian Math
Bulletin, numerous refereeing jobs for papers and dissertations.
## Graduate Students

R. Yahaghi, Reducibility questions (current).
M.T. Jahandideh, Invariant Ideals of Operators on Banach Lattices, Ph. D.,
1997.
A. Marwaha, Structure of Positive Bands, Ph. D., 1996
A. Simonic, An extension of Lomonosov Techniques to Non-compact Operators,
Ph.D., 1994.
T. Quinn, Factorization in C*-algebras: Products of Positive Operators,
Ph.D., 1992.
Y. Zhong, Functional Positivity and Invariant Subspaces of Semigroups of
Operators, Ph.D., 1992.