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Heydar Radjavi

Adjunct Professor

Contact information

Department of Pure MathematicsHeydar Radjavi
University of Waterloo
Waterloo, Ontario
Canada N2L 3G1

Office room number: Mathematics & Computer (MC) 5424
Office telephone number: 519-888-4567 ext. 37509
​Email: hradjavi@uwaterloo.ca
 

 Research interests

  • Operator theory
  • Linear algebra

Education

  • PhD (Minnesota)
 

Full list of publications by Heydar Radjavi


(i) PAPERS:

  • Hilbert space operators with compatible off-diagonal corners (with L. Livshits, G. MacDonald, and L. Marcoux), J. Funct. Anal. 275 (2018), 892-925.
  • Common invariant subspaces from small commutators (with A. Jafarian and A.Popov), Indiana Univ. Math. J. 67 (2018), 151-167.
  • Reducibility of operator semigroups and values of vector states (with L. Marcoux, and B. Yahaghi), Semigroup Forum 95 (2018), 126-158.
  • Matrix semigroups whose ring commutators have real spectra are realizable (with M. Mastnak), Semigroup Forum 95 (2017), 51-65.
  • A Perron-Frobenius-type theorem for positive matrix semigroups (with L. Livshits and M. MacDonald), Positivity 21 (2017), 61-72.
  • An extension of a theorem of Kaplansky (with B. Yahaghi), Comm. Algebra 45 (2017)1668-1674.
  • Ranges of vector states on irreducible operator semigroups (with L. Marcoux, M. Omladic, A. Popov, and B. Yahaghi), Semigroup Forum 93 (2016), 264–304.
  • On selfadjoint extensions of semigroups of partial isometries (with J. Bernik, L. Marcoux, and A. Popov), Trans. Amer. Math. Soc. 368 (2016), 7681–7702.
  • Near-invariant subspaces for matrix groups are nearly invariant (with M. Mastnak and M. Omladic), Linear Alg. Appa. 505 (2016), 269–281.
  • Universal bounds for positive matrix semigroups (with L. Livshits and G. MacDonald), Studia Math. 232 (2016),143-153.
  • Invariant and almost-invariant subspaces for pairs of idempotents (with J. Bernik), Integral Eqartions Operator Theory 84 (2016), 283-288.
  • Nilpotent commutators with a masa (with M. Mastnak and M. Omladic), J. Operator Theory 74 (2015), 371-389.
  • A theorem of Kaplansky revisited (with B. Yahaghi), Lin. Alg. Appl. 487 (2015), 268-275.
  • A simultaneous Wielandt positivity theorem (with G. MacDonald), Positivity 19 (2015), 149-160.
  • A spatial version of Wedderburn’s principal theorem (with L. Livshits, G. MacDonald, and L.W. Marcoux), Lin. Multilin. Alg. 63 (2015), 1216-1241.
  • Commutators of small rank and reducibility of operator semigroups (with A. Jafarian, A. Popov, and M. Radjabalipour), Proc. Amer. Mat. Soc.142 (2014), 4277-4289.
  • Semigroups of partial isometries (with A. Popov), Semigroup Forum 87 (2013), 663-678. (See also Erratum, Semigroup Forum 87 (2013), 679-680).
  • Paratransitive algebras of linear operators II (with L. Livshits, G. MacDonald, and L.W. Marcoux), Lin. Alg. Appl. 439 (2013), 1974-1989.
  • Paratransitive algebras of linear operators (with L. Livshits, G. MacDonald, and L.W. Marcoux), Lin. Alg. Appl. 439 (2013), 1955-1973.
  • Multiplicative maps that are close to an automorphism on algebras of linear transformations (with L.W. Marcoux and A. Sourour), Studia Math. 214 (2013), 279-296.
  • On semigroups of nonnegative functions and positive operators (with R. Drnovsek), J. Math. Anal. Appl. 404 (2013), 29-35.
  • On almost invariant subspaces and approximate commutation (with L.W. Marcoux and A. Popov), J. Func. Anal. 264 (2013), 1088-1111.
  • On irreducible algebras spanned by triangularizable matrices (with B. Yahaghi), Lin. Alg. Appl.436 (2012), 2001-2007.
  • Finite groups with submultiplicative spectra (with L. Grunenfelder, T. Kosir, and M. Omladic), J. Pure & Appl. Alg. 216 (2012) 1196-1206.
  • Self-adjoint semigroups with nilpotent commutators (with M. Omladic), Lin. Alg. Appl. 436 (2012), 2597-2603.
  • Spectral conditions and band reducibility of operators (with J. Bernik and L.W. Marcoux), J. London Math Soc.(2) 86 (2012), 214-234.
  • Positive matrix semigroups with binary diagonals (with L. Livshits and G. MacDonald), Positivity 15 (2011), 411-440.
  • Multiplicative diagonals of matrix semigroups (with L. Livshits and G. MacDonald), Electron. J. Lin. Alg. 22 (2011), 252-266.
  • Universal bounds on matrix semigroups (with L. Livshits and G. MacDonald), Studia Math. 203 (2011), 69-77.
  • Nonnegative matrix semigroups with finite diagonals (with A. Popov and P. Williamson), Lin. Alg. Appl. 434 (2011), 1409-1424.
  • On semitransitive Jordan algebras of matrices (with J. Bernik, R. Drnovsek, D. Kokol Bukovsek, T. Koshir, and M. Omladic), J. Alg. Appl. 10 (2011), 319-333.
  • Positivity and matrix semigroups (with J. Bernik and M. Mastnak), Lin. Alg. Appl. 434 (2011), 801-812.
  • Bounded indecomposable semigroups of nonnegative matrices (with H. Gessesse, A. Popov, E. Spinu, A. Tcaciuc, and V. Troitsky), Positivity 14 (2010), 383-394.
  • Paul Halmos and invariant subspaces, a glimpse at Hilbert space operators (with P. Rosenthal), Oper. Theory Adv. Appl. 207 Birkhäuser Verlag, Basel, 2010, 341–349
  • Nil polynomials and reducibility of operator semigroups, J. Operator Theory 64 (2010), 245-264.
  • Stochastic operators and extreme points (with D. Hadwin and E. Nordgren), Oper. Matrices 3 (2009), 227-233.
  • Invariant sublattices (with V. Troitsky), Illinois J. Math. 52 (2009), 463-472.
  • Nilpotent commutators and reducibility of semigroups (with M. Omladic), Lin. & Multilin. Alg. 57 (2009), 307-317.
  • Semitransitive spaces of operators (with V.G. Troitsky), Lin. Multilin. Alg. 57 (2009), 1-11.
  • Triangularizability of operators with increasing spectrum (with L.W. Marcoux and M. Mastnak), J. Funct. Anal. 257 (2009), 3517-3540.
  • Spectral conditions on Lie and Jordan algebras of compact operators (with M. Kennedy), J. Funct. Anal. 256 (2009), 3143-3157.
  • Structure of finite, minimal nonabelian groups and triangulaization (with M. Mastnak), Lin Alg Appl. 430 (2009), 1838-1848.
  • Realizing irreducible semigroups and real algebras of compact operators (with J. Bernik and M. Mastnak), J. Math. Anal. Appl. 348 (2008) 692-707.
  • Transitive spaces of operators (with K. Davidson and L. Marcoux), Intg. Eq. & Oper. Theory 61 (2008), 187-210.
  • Sesquitransitive and localizing operator algebras (with V. Lomonosov and V. Troitsky), Integ. Eq. & Oper.Theory 60 (2008), 405-418.
  • Linear maps preserving quasicommutativity (with P. Semrl), Studia Math. 184 (2008), 191-204.
  • On the topological stable rank of non-selfadjoint operator algebras (with K. Davidson, R. Levene, and L. Marcoux), Math. Ann. 341 (2008), 239-253.
  • A Kadison transitivity theorem for C*-semigroups (with L. Livshits, G. MacDonald, and L. Marcoux), J. Funct. Anal. 254 (2008), 246-266.
  • Limitations on the size of semigroups of matrices (with P. Rosenthal), Semigroup Forum 76 (2008), 25-31.
  • Approximate permutability of traces on semigroups of matrices (with J. Bernik, R. Drnovsek, T. Kosir, L. Livshits, M. Mastnak, and M. Omladic), Oper. Matrices 4 (2007), 455-467.
  • Topologically transitive matrix semigroups (with L. Livshits and G. MacDonald), Oper. Matrices 1 (2007), 165-179.
  • The semigroup generated by the unitary orbit of a singular matrix (with A.R. Sourour), Lin & Multilin. Alg. 55 (2007), 417-428.
  • On submultiplicativity of spectral radius and transitivity of semigroups (with P. Rosenthal), Proc. Amer. Math. Soc. 135 (2007), 163-168.
  • An approximate, multivariable version of Specht's theorem (with L.W. Marcoux and M. Mastnak), Lin. Multilin. Alg. 55 (2007), 159-174.
  • On the diameters of commuting graphs (with S. Akbari, A. Mohammadian, and P. Raja), Linear Alg. Appl. 418 (2006), 161-176.
  • A function arising in the estimatation of Unobserved Probability (with C.C.A. Sastri), Statist. Probab.  Lett. 76 (2006), 682-688.
  • Transitive actions of Lie algebras (with L. Grunenfelder and M. Omladic), J. Pure Appl.Alg. 199 (2005), 87-93.
  • Polynomial conditions on operator semigroups, J. Operator Theory 53 (2005), 197-220.
  • How small can nonzero commutators be? (with J. Bernik), Indiana Univ. Math. J. 54 (2005), 309-320.
  • On semitransitive collections of operators (with J. Bernik, L. Grunenfelder, M. Mastnak, and V. Troitsky), Semigroup Forum 70 (2005), 436-450.
  • Common fixed points and common eigenvectors for sets of matrices (with J. Bernik, R. Drnovsek, T. Kosir, T. Laffey, G. MacDonald, R. Meshulam, and M. Omladic), Lin. Multilin. Alg. 53 (2005), 137-146.
  • Standard Triangularization of semigroups of nonnegative operators (with G. MacDonald), J. Funct. Anal. 219 (2005), 161-176.
  • Non-linear maps preserving solvability (with P. Semrl), J. Algebra 280 (2004), 624-634.
  • On Rings of Matrices Over Division Rings (with M. Radjabalipour), Lin. Multilin. Alg. 52 (2004), 375-380.
  • Matrix Semigroups with Commutable Rank (with L. Livshits, G. MacDonald, B. Mathes, and J. Okninski), Semigroup Forum 67 (2003), 288-316.
  • Trace-preserving homomorphisms of semigroups (with M. Hladnik and M. Omladic), J. Funct. Analysis 204 (2003), 269-292.
  • Irreducible semigroups of matrices with eigenvalue one (with J. Bernik, R. Drnovsek, T. Kosir, and M. Omladic), Semigroup Forum 67 (2003), 271-287.
  • A short proof of Hua's fundamental theorem of the geometry of hermitian matrices (with P. Semrl), Expositiones Math. 21 (2003), 83-93.
  • A perturbation characterization of compactness of self-adjoint operators (with P.K. Tam and K.K. Tan), Studia Math. 158 (2003), 199-205.
  • Mean ergodicity for compact operators (with P.K. Tam and K.K. Tan),Studia Math. 158 (2003), 207-217.
  • Operator semigroups for which reducibility implies decomposibility (with L. Livshits, G. MacDonald. and B. Mathes), Positivity 7 (2003), 195-202.
  • Inference for annotated logics over distributive lattices (with J.L. Lu, N.V. Murray, E. Rosenthal, and P. Rosenthal), Proceedings of the 13th International Symposium on Methodologies for Intelligent Systems, Springer Lecture notes, ISMIS 2002: 285-293.
  • On commutators of idempotents (with P. Rosenthal), Lin. Multilin. Alg. 50 (2002), 121-124.
  • Maximal Jordan algebras of matrices with bounded number of eigenvalues (with L. Grunenfelder, T. Kosir, and M. Omladic), Is. J. Math. 128 (2002), 53-75.
  • Intersections of nest algebras in finite dimensions (with P.A. Fillmore, W.E. Longstaff, G.W. MacDonald, and Y. Zhong), Lin. Alg. Appl. 350 (2002), 185-197.
  • A characterization of commutators of idempotents (with R. Drnovsek and P. Rosenthal), Lin. Alg. Appl. 347 (2002), 91-99.
  • On compactness of the best approximant set (with H. Mohebi), J. Nat. Geom. 21 (2002), 51-62.
  • An irreducible semigroup of nonnegative squar-zero operators (with R. Drnovsek, D. Kokol-Bukovsek, L. Livshits, G. MacDonald, and M. Omladic), Integr. Equ. Oper. theory 42 (2002), 440-460.
  • Inequalities for products of spectral radii (with M. Omladic, P. Rosenthal, and A. Sourour), Proc. Amer. Math. Soc. 129 (2001), 2239-2243.
  • Products of roots of the identity (with M. Hladnik and M. Omladic), Proc. Amer. Math. Soc. 129 (2001), 459-465.
  • Semigroups generated by similarity orbits (with L. Grunenfelder, M. Omladic, and A. Sourour), Semigroup Forum 62 (2001), 460-472.
  • On band algebras (with L. Livshits, G. MacDonald, and B. Mathes), J. Operator Theory 46 (2001), 545-560.
  • Preserving commutativity (with M. Omladic and P. Semrl), J. Pure & Appl. Alg. 156 (2001), 309-328.
  • Operator semigroups with quasinilpotent commutators (with P. Rosenthal and V. Shulman), Proc. Amer. Math. Soc. 128 (2000), 2413-2420.
  • Cone-transitive matrix semigroups (with L. Livshits and G. MacDonald), Lin. & Multilin. Alg. 47 (2000), 313-350.
  • On operator bands (with R. Drnovsek, L. Livshits, G. MacDonald, B. Mathes, and P. Semrl), Studia Math. 139 (2000), 91-100.
  • On transitive linear semigroups (with R. Drnovsek, L. Livshits, G. MacDonald, B. Mathes, and P. Semrl), Lin. Alg. & Appl. 305 (2000), 67-86.
  • Sublinearity and other spectral conditions on a semigroup, Canad. J. Math. 5 (2000), 197-224.
  • Mean ergodic theorems for affine operators (with P.K. Tam and K.K. Tan), Math. Comput. modeling 32 (2000), 1417-1421.
  • Homomorphisms from C* into GLn(C) (with M. Omladic and P. Semrl), Pub. Math. Debrecen 55 (1999), 479-486.
  • On the operator equation AX = XAX (with J. Holbrook, E. Nordgren and P. Rosenthal), Lin. Alg. &Appl. 295 (1999), 113-116.
  • The Perron-Frobenius Theorem revisited, Positivity 3 (1999), 317-331.
  • A finiteness lemma, Brauer's Theorem and other irreducibility results (with M. Radjabalipour), Communications in Algebra 27(1) (1999), 301-319.
  • Principal-ideal bands (with P. Fillmore, G. MacDonald, and M. Radjabalipour), Semigroup Forum 59 (1999), 362-373.
  • Idempotent completions of partial operator matrices (with J. Hou and P. Rosenthal), Acta Math. Sinica (English Series) 15 (1999), 333-346.
  • On groups generated by elements of prime order (with L. Grunenfelder, T. Koshir, and M. Omladic), Geometriae Dedicata 75 (1999), 317-332.
  • Invariant subspaces for semigroups of algebraic operators (with G. Cigler, R. Drnovsek, D. Kokol-Bukavsek, T. Laffey, M. Omladic, and P. Rosenthal), J. Functional Analysis 160 (1998), 452-465.
  • Boundedness stability properties of linear and affine operators (with M. Edelstein and K.K. Tan), Taiwanese J. Math. 2 (1998), 111-125.
  • Reducible semigroups of idempotent operators (with L. Livshits, G. MacDonald, and B. Mathes), J. Operator Theory 40 (1998), 35-69.
  • From local to global triangularization (with P. Rosenthal), J. Functional Analysis 147 (1997), 443-456.
  • Maximal semigroups dominated by 01 matrices (with T. Kosir and M. Omladic), Semigroup Forum 54 (1997), 125-189.
  • Permutability of characters on algebras (with L. Grunenfelder, R. Guralnick and T. Kosir), Pacific J. Math. 178 (1997), 63-70.
  • Invariant subspaces and spectral conditions on operator semigroups, Polish Acad. Sciences, Banach Center Publications, Polish Academy of Sciences, 38 (1997), 287-296.
  • Irreducible semigroups with multiplicative spectral radius (with M. Omladic), Linear Alg. Appl.251 (1997), 59-72.
  • Local polynomials are polynomials (with C.K. Fong, G. Lumer, E. Nordgren, and P. Rosenthal), Studia Math. 115 (1995), 105-107.
  • On permutability and submultiplicativity of spectral radius (with W. Longstaff), Canadian J. Math. 47 (1995), 1007-1022.
  • Simultaneous triangularizability, near-commutativity, and Rota's theorem (with A.A. Jafarian, P. Rosenthal, and A.R. Sourour), Trans. Amer. Math. Soc. 347 (1995), 2191-2199.
  • Local multiplications on algebras spanned by idempotents (with D. Hadwin, A. Jafarian, C. Laurie, E. Nordgren, and P. Rosenthal), Linear and Multilin. Alg. 37 (1994), 259-263.
  • Toward a classification of maximal unicellular bands (with P. Fillmore, G. MacDonald, and M. Radjabalipour), Semigroup Forum 49 (1994), 195-215.
  • On semigroups of matrices with traces in a subfield (with M. Omladic and M. Radjabalipour), Linear Alg. & Appl. 208-209 (1994), 419-424.
  • On sums of idempotents (with C. Laurie and B. Mathes), Linear Alg. & Appl. 208/209(1994), 175-197.
  • Approximation by products of positive operators (with C. Laurie, M. Khalkhali, and B. Mathes), J. Oper. Theory 29 (1993), 237-247.
  • Jordan analogs of the Burnside and Jacobson Theorems (with L. Grunenfelder and M. Omladic), Pac. J. Math. 161 (1993), 335-346.
  • Triangularizing semigroups of operators with non-negative entries (with M.D. Choi, E. Nordgren, P. Rosenthal, and Y. Zhong), Indiana Univ. Math J. 42 (1993), 15-25.
  • Spectral conditions and reducibility of operator semigroups (with M. Lambrou and W. Longstaff), Indiana Univ. Math. J. 41 (1992) 449-464.
  • On simultaneous triangularization of collections of operators (with D. Hadwin, E. Nordgren, M. Radjabalipour, and P. Rosenthal), Houston J. Math. 17(1991), 581-602.
  • Linear spaces of nilpotent matrices (with B. Mathes and M. Omladic), J. Lin. Alg. & Appl. 149 (1990), 215-225.
  • On reducibility of semigroups of compact operators, Indiana University Math. J. 39 (1990), 499-515.
  • On complementary matrix algebras (with M.D. Choi and P. Rosenthal), Integral Equations & Operator Theory 13 (1990), 165-174.
  • Simultaneous triangularization of operators on a Banach space (with A. Katavolos), J. London Math. Soc. (2) 41 (1990), 547-554.
  • Weak resolvents of linear operators II (with C.K. Fong, E. Nordgren and P. Rosenthal), Indiana University Math. J.39 (1990), 67-83.
  • On the equation AB = BX in collections of matrices (with W.E. Longstaff), Linear & Multilinear Alg., 25 (1989), 173-184.
  • A similarity invariant (with C.K. Fong, E. Nordgren, and P. Rosenthal), Proc. Sympos. Pure Math. 51, Part 2, Amer. Math. Soc. (1990), 99-101.
  • Weak resolvents of linear operators (with E. Nordgren and P. Rosenthal), Indiana University Math. J. 36 (1987), 913-934.
  • The Engel-Jacobson theorem revisited, J. Algebra 111 (1987), 427-430.
  • On the congruence numerical range and related functions of matrices (with M.D. Choi, C. Laurie, and P. Rosenthal), Lin. Multilin. Alg. 22 (1987), 1-5.
  • Quadratic operators and invariant subspaces (with E. Nordgren and P. Rosenthal), Studia Math. 88 (1988), 263-268.
  • Norms for matrices and operators (with C.K. Fong and P. Rosenthal), J. Operator Theory 18 (1987), 99-113.
  • Operators with commutative commatants (with M. Radjabalipour), Michigan Math. J. 35 (1988), 127-131.
  • Linear maps preserving commutativity (with M.D. Choi and A.A. Jafarian), J. Linear Alg. Appl. 87 (1987), 227-241.
  • Orbit-reflexive operators (with D. Hadwin, E. Nordgren and P. Rosenthal), J. London Math. Soc. (2) 34 (1986), 111-119.
  • A nil algebra of bounded operators on Hilbert space with semisimple norm closure (with D. Hadwin, E. Nordgren, M. Radjabalipour and P. Rosenthal), Integral Equations & Operator Theory 9 (1986), 239-243.
  • A trace condition equivalent to simultaneous triangularizability, Canadian J. Math. 38 (1986), 376-386.  MR 87f: 47058.
  • Density and transitivity results on l^infinity and l^1 (under the acronym "R.B. Honor" with J. Borwein, D. Hadwin, E. Nordgren, R. O'Brien, M. Orhon  and P. Rosenthal), J. London Math. Soc. 32 (1985), 521-527.
  • On matrix spaces with zero determinant (with P. Fillmore and C. Laurie), Linear & Multilinear Alg. 18 (1985), 341-352.
  • On the reduction and triangularization of semigroup of operators, J. Operator Theory 13 (1985), 63-71.
  • On fixed points of semigroups of linear contractions (with P. Rosenthal), Proc. Amer. Math. Soc. 93 (1985), 640-642.
  • On positive maps preserving invertibility (with M.D. Choi, D. Hadwin, E. Nordgren and P. Rosenthal), J. Functional Analysis 59 (1984), 462-469.
  • Commutativity-preserving operators on symmetric matrices, J. Linear Alg. & Appl. 61 (1984), 219-224.
  • On a commutator theorem of R.C. Thompson (with L. Grunenfelder and R. Pare), J. Linear & Multilinear Alg. 16 (1984), 129-131.
  • On positive maps preserving invertibility (with M.D. Choi, D. Hadwin, E. Nordgren and P. Rosenthal), J. Functional Analysis 59 (1984), 462-469.
  • Commutativity-preserving operators on symmetric matrices, J. Linear Alg. & Appl. 61 (1984), 219-224.
  • Triangularizing semigroups of compact operators (with E. Nordgren and P. Rosenthal), Indiana Univ. Math. J. 33 (1984), 271-275.
  • On minimal invariant manifolds and density of operator algebras, Acta. Scient. Math. (Szeged) 47 (1984), 113-115.
  • Associative and Lie subalgebras of finite codimension (with G.J. Murphy), Studia Math. 76(1983), 81-85.
  • On ideals and Lie ideals of compact operators (with C.K. Fong), Math Annalen 262 (1983), 23-28.
  • The invariant subspace problem (with P. Rosenthal), Math. Intelligencer 4 (1982), 33-37.
  • On triangularization of algebras of operators (with C. Laurie, E. Nordgren and P. Rosenthal), J. Reine Angus Math. 327(1981), 143-155.
  • Proof of Balantine's conjecture on simplic cosquares, J. Linear & Multilinear Algebra 9(1980), 193-194.
  • The group generated by involutions, Proc. Royal Irish Acad. 81A (1981), 9-12.
  • On commutators and invariant subspaces (with M.D. Choi and C. Laurie), J. Linear and Multilinear Alg. 9 (1981), 329-340.
  • An operator not satisfying Lomonosov's hypothesis (with D. Hadwin, E. Nordgren and P. Rosenthal), J. Functional Analysis 38 (1980), 410-41.
  • Extensions of Lomonosov's invariant subspace theorem (with C.K. Fong, E. Nordgren, M. Radjabalipour and P. Rosenthal), Acta Scient. Math. (Szeged) 41 (1979), 55-62.
  • On the West decomposition of Riesz operators (with C. Laurie), Bull. London Math. Soc.12 (1980), 130-132.
  • How general is Lomonosov's invariant subspace theorem? (with P. Rosenthal) Math. Reports of the Acad. Sci., Royal Society of Canada 1 (1979),29-31.
  • On density of algebras with minimal invariant operator ranges, Proc. Amer. Math. Soc. 68 (1978), 189-192.
  • Most similarity orbits are strongly dense (with D. Hadwin, E. Nordgren and P. Rosenthal), Proc. Amer. Math. Soc. 76 (1979), 250-252.
  • Compact operator ranges and transitive algebras (with M. Radjabalipour), J. London Math. Soc. (2), 17 (1978), 522-524.
  • Compact operator ranges and reductive algebras (with A.A. Jafarian), Act. Scient. Math. (Szeged) 40 (1978), 73-79.
  • On invariant operator ranges (with E. Nordgren, M. Radjabalipour and P. Rosenthal), Trans. Amer. Math. Soc. 25 (1979), 379-398.
  • Reductive algebras with minimal ideals, Math. Annalen 219 (1976), 227-231.
  • On invariant subspaces of compact perturbation of operators (with M. Radjabalipour), Rev. Roum. Math. Pures Appl. 21 (1976), 1247-1260.
  • A geometric equivalent of the invariant subspace problem (with E. Nordgren and P. Rosenthal), Proc. Amer. Math. Soc. 61 (1976), 66-68.
  • Operator algebras leaving compact operator ranges invariant (with E. Nordgren and P. Rosenthal), Mich. Math. J. 23 (1976), 375-377.
  • On chromatic numbers of infinite graphs (with M. Behzad), J. Combin. Theory, Ser.B. 21(1976), 195-200.
  • On Arveson's characterization of hyperreducible triangular algebras (with E. Nordgren and P. Rosenthal), Indiana Univ. Math. J. 26 (1977), 179-182.
  • Algebras intertwining compact operators (with E. Nordgren, M. Radjabalipour and P. Rosenthal), Acta Scient. Math. (Szeged) 39(1977), 115-119.
  • On the geometry of numerical ranges (with M. Radjabalipour), Pac. J. Math. 61 (1975), 507-511.
  • Decomposition of matrices into simple involutions, Linear Algebra and Appl. 12 (1975), 247-255.
  • On decomposability of compact perturbations of normal operators (with M. Radjabalipour), Can. J. Math. 27 (1975), 725-735.
  • Products of Involutions (with W. Gustafson and P.R. Halmos), Linear Algebra and Appl. 13( 1976), 157-162.
  • Non-self-adjoint representations of C*-algebras, Proc. Amer. Math. Soc. 47(1975), 133-136.
  • Isomorphisms of transitive operator algebras, Duke Math. J. 41 (1974), 555-564.
  • On operators with reducing invariant subspaces (with E. Nordgren and P. Rosenthal), Amer. J. Math. 97 (1975), 559-570.
  • On transitive and reductive operator algebras (with P. Rosenthal), Math. Ann. 209 (1974), 43-56.
  • Invariant subspaces for products of Hermitian operators (with P. Rosenthal), Proc. Amer. Math. Soc. 43 (1974), 483-484.
  • Graphs with isomorphic subgraphs (with P. Rosenthal), J. London Math. Soc., (2), 6 (1972), 70-72.
  • A sufficient condition that an operator algebra be self-adjoint (with P. Rosenthal), Can. J. Math. 23 (1971), 588-597.
  • On roots of normal operators (with P. Rosenthal), J. Math. Analysis and Appl. 34 (1971), 653-664.
  • Hyperinvariant subspaces for spectral and n-normal operators (with P. Rosenthal), Acta Sci. Math. (Szeged) 32 (1971), 121-126.
  • On reflexive algebras of operators (with P. Rosenthal), Report to the International Symposium on Operator Theory at Indiana University (1970), Indiana University Math. J. 20 (1971), 935-937.
  • A transitive medial subspace lattice (with K.J. Harrison and P. Rosenthal), Proc. Amer. Math. Soc. 28 (1971), 119-121.
  • Structure of regular total graphs (with M. Behzad), J. London Math. Soc. 44 (1969), 433-436.
  • Another analog of Ramsey numbers (with M. Behzad), Math. Ann. 186 (1970), 228-232.
  • The line analog of Ramsey numbers (with M. Behzad), Israel J. Math. 5 (1967), 93-96.
  • The total group of a graph (with M. Behzad), Proc. Amer. Math. Soc. 19 (1968), 158-163.
  • Products of self-adjoint operators (with J.P. Williams), Mich. Math. J. 16 (1969), 177-185.
  • On density of transitive algebras (with E. Nordgren and P. Rosenthal), Acta. Sci. Math.(Szeged) 30 (1969), 175-179.
  • Matrices for operators and generators of B(H) (with P. Rosenthal), J. London Math. Soc. (2), 2 (1970), 557-560.
  • On operator algebras and invariant subspaces (with C. Davis and P. Rosenthal), Can. J. Math. 21 (1969), 1178-1181.
  • The set of irreducible operators is dense (with P. Rosenthal), Proc. Amer. Math. Soc. 21 (1969), 256.
  • On invariant subspaces and reflexive algebras (with P. Rosenthal), Amer. J. Math. 91 (1969), 683-692.
  • Products of Hermitian matrices and symmetries, Proc. Amer. Math. Soc. 21 (1969), 369-372.
  • On self-adjoint factorization of operators, Can. J. Math. 21(1969), 1421-1426.
  • Every operator is the sum of two irreducible ones, Proc. Amer. Math. Soc. 21 (1969), 251-252.
  • Invariant subspaces and weakly closed algebras (with P. Rosenthal), Bull. Amer. Math.Soc.74 (1968), 1013-1014.
  • Simultaneous unitary invariants for sets of matrices, Can. J. Math. 20 (1968), 1012-1019.
  • Structure of A*A - AA*, J. Math. Mech. 16 (1966), 19-26.
  • On unitary equivalence of arbitrary matrices, Trans. Amer. Math. Soc. 104 (1962), 363-373.

(ii) BOOKS:

  • French Hats in Iran, Mage Publishers, Washington DC, 2011.
  • Second edition of Invariant Subspaces by Dover Publications, 2003.
  • Simultaneous Trianqularizability (with P. Rosenthal), Universitext, Springer, New York, 2000.
  • Invariant Subspaces (with P. Rosenthal), Ergebnisse der Mathematik und ihrer Grenzgebiete 77, Springer-Verlag, Heidelberg, New York. (1973)
Affiliation: 
University of Waterloo

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