Peter Rosenthal

Peter Michael Rosenthal
Born	(1941-06-01)June 1, 1941 Queens, New York, U.S.
Died	May 25, 2024(2024-05-25) (aged 82) Toronto, Canada
Citizenship	Canadian American
Occupation(s)	Mathematician, lawyer
Spouses	Helen Stephanie Rosenthal ​ ​ (m. 1960; div. 1979)​ Carol Kitai ​ (m. 1985)​
Children	Alan Rosenthal, Jeffrey S. Rosenthal, Michael Rosenthal, Daniel Kitai Rosenthal, Esther Kitai Rosenthal
Academic background
Education	Queens College, CUNY (BS) University of Michigan (PhD) University of Toronto (LLB)
Thesis	On Latices of Invariant Subspaces (1967)
Doctoral advisor	Paul Halmos
Academic work
Institutions	University of Toronto

Peter Michael Rosenthal (June 1, 1941 – May 25, 2024) was a Canadian-American Professor of Mathematics at the University of Toronto, an adjunct professor of Law at the University of Toronto, and a lawyer in private practice.

Early life

Rosenthal grew up in a Jewish family in Flushing, Queens, New York with his parents, Harold and Esther, and two brothers. His father was a high school math teacher and his mother was a "flaming radical". He had poor grades in high school and barely graduated, but after nearly failing in college due to the time he spent attending civil rights and anti-nuclear protests, he began to focus on his studies at Queens College, excelling in math. He married his first wife, Helen, in 1960 when he was 19 and she was 18. They would divorce in 1979. He married his second wife, Carol Kitai, in 1985.

Rosenthal was a lifelong Marxist and political activist. He was a red diaper baby; his mother was active in the civil rights and anti-war movements. Rosenthal told the Globe and Mail: "I regard myself as a Marxist, but not one affiliated with any particular parties... I have a very strong hatred of racism and the grotesque economic inequalities such as exist in the world. It is very deeply embedded in my bones."

Mathematics career

Rosenthal graduated from Queens College, City University of New York with a B.S. in Mathematics in 1962. In 1963 he obtained an MA in Mathematics and in 1967 a Ph.D. in Mathematics from the University of Michigan; his Ph.D. thesis advisor was Paul Halmos. His thesis, "On lattices of invariant subspaces" concerns operators on Hilbert space, and most of his subsequent research was in operator theory and related fields. Much of his work was related to the invariant subspace problem, the still-unsolved problem of the existence of invariant subspaces for bounded linear operators on Hilbert space. He made substantial contributions to the development of reflexive and reductive operator algebras and to the study of lattices of invariant subspaces, composition operators on the Hardy-Hilbert space and linear operator equations. His publications include many with his long-time collaborator Heydar Radjavi, including the book "Invariant subspaces" (Springer-Verlag, 1973; second edition 2003).

Rosenthal supervised the Ph.D. theses of fifteen students and the research work of a number of post-doctoral fellows.

Legal career

In parallel with his career in mathematics, Rosenthal pursued a career in law. While teaching at the University of Toronto in 1969, Rosenthal was arrested while giving a speech at an anti-war demonstration outside of the US consulate in Toronto. Representing himself in court, he was acquitted of obstructing police but convicted of causing a disturbance, but was able to have his conviction overturned on appeal. With his newfound interest in the law, Rosenthal began volunteering as a paralegal representing friends and activists who had been arrested and charged with minor criminal offences at protests and for civil disobedience. Rosenthal was threatened by the Law Society of Upper Canada for practicing law without a license and he hired Charles Roach to represent him before the law society. The law society abandoned its action after Roach moved a motion to move the disciplinary proceeding to court. Roach encouraged Rosenthal to go to law school so that he could represent clients in more serious cases, and he admitted to University of Toronto Law School in 1988 at the age of 47. He went on to obtain an LL.B. in 1990 and was called to the Ontario Bar in 1992. He was a major figure in the Toronto legal community, and was profiled by Toronto Life, The Globe and Mail, and the Toronto Star In 2006, Now Magazine named Rosenthal Toronto's "Best activist lawyer". In May 2016, he was awarded a Law Society Medal by the Law Society of Upper Canada.

Rosenthal provided legal services for various leftist causes for free. He was also active in civil law suing police and public officials.

Rosenthal represented Miguel Figueroa, the leader of the Communist Party of Canada, in the case Figueroa v. Canada before the Supreme Court of Canada. The court ruled in Figueroa's favor, striking down a law that prohibited small political parties from obtaining the same tax benefits as large parties.

He represented many activists who faced charges as a result of political protests, including Shawn Brant, John Clarke and the Ontario Coalition Against Poverty, Vicki Monague of Stop Dump Site 41, Dudley Laws, and Jaggi Singh, and wrote articles about some of those cases. In 2006, Rosenthal represented Indigenous activists at the Ipperwash Crisis and cross-examined former Premier of Ontario Mike Harris over allegedly saying ""I want the fucking Indians out of the park."

Works

• Radjavi, Heydar; Rosenthal, Peter (1973), Invariant Subspaces, Springer, MR 0367682, 2nd edition MR2003221
• Radjavi, Heydar; Rosenthal, Peter (2000), Simultaneous Triangularization, Springer, ISBN 978-0-387-98466-7
• Martinez-Avendano, Ruben; Rosenthal, Peter (2006), An Introduction to Operators on the Hardy-Hilbert Space, Springer, ISBN 978-0-387-35418-7
• (with Sheldon Axler and Donald Sarason) editors. A Glimpse at Hilbert Space Operators, Birkhäuser, 2010.
• Rosenthal, Daniel; Rosenthal, David; Rosenthal, Peter (2014), A Readable Introduction to Real Mathematics, Springer, ISBN 978-3-319-05654-8, MR 3235953