Peter Michael Rosenthal (June 1, 1941 – May 25, 2024) was an American-Canadian mathematician, lawyer, and activist who was Professor of Mathematics at the

University of Toronto The University of Toronto (UToronto or U of T) is a public university, public research university whose main campus is located on the grounds that surround Queen's Park (Toronto), Queen's Park in Toronto, Ontario, Canada. It was founded by ...

, and an adjunct professor of Law at the

University of Toronto Law School The University of Toronto Faculty of Law (U of T Law, UToronto Law) is the law school of the University of Toronto, located at the University of Toronto#St. George campus, St. George campus in Downtown Toronto. It is the top ranked common law facu ...

Early life and family

Rosenthal grew up in a Jewish family in

Flushing Flushing may refer to: Places Netherlands * Flushing, Netherlands, an English name for the city of Vlissingen, Netherlands United Kingdom * Flushing, Cornwall, a village in Cornwall, England * The Flushing, a building in Suffolk, England ...

Queens Queens is the largest by area of the Boroughs of New York City, five boroughs of New York City, coextensive with Queens County, in the U.S. state of New York (state), New York. Located near the western end of Long Island, it is bordered by the ...

, New York with his parents, Harold (1913–1983) and Esther (1914–1985), and two younger brothers, Erik and Walter. Rosenthal described himself as a " red diaper baby". His father was a high school math teacher and his mother was a left-wing activist who had been a member of the Communist Party in her youth. His maternal grandmother, Sonia, had immigrated to New York from Russia after the failed

1905 Russian Revolution The Russian Revolution of 1905, also known as the First Russian Revolution, was a revolution in the Russian Empire which began on 22 January 1905 and led to the establishment of a constitutional monarchy under the Russian Constitution of 1906, th ...

and was a supporter of the

Bolshevik The Bolsheviks, led by Vladimir Lenin, were a radical Faction (political), faction of the Marxist Russian Social Democratic Labour Party (RSDLP) which split with the Mensheviks at the 2nd Congress of the Russian Social Democratic Labour Party, ...

s. Rosenthal himself was also a committed activist and in 1960 participated in protests at the Woolworth's in Flushing in solidarity with the sit-ins at Woolworth's in Greensboro, North Carolina protesting racial segregation. Rosenthal had poor grades in high school and barely graduated, but after nearly failing in college due to the time he spent attending

civil rights Civil and political rights are a class of rights that protect individuals' political freedom, freedom from infringement by governments, social organizations, and private individuals. They ensure one's entitlement to participate in the civil and ...

and

anti-nuclear The Anti-nuclear war movement is a social movement that opposes various nuclear technologies. Some direct action groups, environmental movements, and professional organisations have identified themselves with the movement at the local, n ...

protests, he began to focus on his studies at

Queens College Queens College (QC) is a public college in the New York City borough of Queens. Part of the City University of New York system, Queens College occupies an campus primarily located in Flushing. Queens College was established in 1937 and offe ...

, excelling in math. Erik Rosenthal is an emeritus professor of mathematics at the

University of New Haven The University of New Haven (UNH) is a private university in West Haven, Connecticut, United States. History The University of New Haven was founded in 1920 as the New Haven YMCA Junior College, a division of Northeastern University, which sha ...

. Their youngest brother, Walter (Wally) Rosenthal, is a community activist and trade unionist in

New York City New York, often called New York City (NYC), is the most populous city in the United States, located at the southern tip of New York State on one of the world's largest natural harbors. The city comprises five boroughs, each coextensive w ...

who taught at York College after retiring from the

United States Postal Service The United States Postal Service (USPS), also known as the Post Office, U.S. Mail, or simply the Postal Service, is an independent agencies of the United States government, independent agency of the executive branch of the federal governmen ...

. Both Erik and Wally were civil rights and anti-war activists in the 1960s.

Mathematics career

Rosenthal graduated from

Queens College, City University of New York Queens College (QC) is a public college in the New York City borough of Queens. Part of the City University of New York system, Queens College occupies an campus primarily located in Flushing. Queens College was established in 1937 and offe ...

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 The University of Michigan (U-M, U of M, or Michigan) is a public university, public research university in Ann Arbor, Michigan, United States. Founded in 1817, it is the oldest institution of higher education in the state. The University of Mi ...

; his Ph.D. thesis advisor was

Paul Halmos Paul Richard Halmos (; 3 March 1916 – 2 October 2006) was a Kingdom of Hungary, Hungarian-born United States, American mathematician and probabilist who made fundamental advances in the areas of mathematical logic, probability theory, operat ...

. His thesis, "On lattices of invariant subspaces" concerns operators on

Hilbert space In mathematics, a Hilbert space is a real number, real or complex number, complex inner product space that is also a complete metric space with respect to the metric induced by the inner product. It generalizes the notion of Euclidean space. The ...

, and most of his subsequent research was in operator theory and related fields. Much of his work was related to the

invariant subspace problem In the field of mathematics known as functional analysis, the invariant subspace problem is a partially unresolved problem asking whether every bounded operator on a complex Banach space sends some non-trivial closed subspace to itself. Many v ...

, 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). In 1967, Rosenthal moved to Canada to accept an assistant professorship at the

where he remained for the rest of his career, eventually becoming a full professor and retiring as a

professor emeritus ''Emeritus/Emerita'' () is an honorary title granted to someone who retirement, retires from a position of distinction, most commonly an academic faculty position, but is allowed to continue using the previous title, as in "professor emeritus". ...

. 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

in 1969, Rosenthal was arrested while giving a speech at an

anti-Vietnam War Opposition to United States involvement in the Vietnam War began in 1965 with demonstrations against the escalating role of the United States in the Vietnam War, United States in the war. Over the next several years, these demonstrations grew ...

demonstration outside of the US

consulate A consulate is the office of a consul. A type of mission, it is usually subordinate to the state's main representation in the capital of that foreign country (host state), usually an embassy (or, only between two Commonwealth countries, a ...

Toronto Toronto ( , locally pronounced or ) is the List of the largest municipalities in Canada by population, most populous city in Canada. It is the capital city of the Provinces and territories of Canada, Canadian province of Ontario. With a p ...

. 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 or for

civil disobedience Civil disobedience is the active and professed refusal of a citizenship, citizen to obey certain laws, demands, orders, or commands of a government (or any other authority). By some definitions, civil disobedience has to be nonviolent to be cal ...

or other activist-related offences, particularly related to

anti-racist Anti-racism encompasses a range of ideas and political actions which are meant to counter racial prejudice, systemic racism, and the oppression of specific racial groups. Anti-racism is usually structured around conscious efforts and delibera ...

activity. Rosenthal was threatened by the

Law Society of Upper Canada The Law Society of Ontario (LSO; ) is the law society responsible for the self-regulation of lawyers and paralegals in the Canadian province of Ontario. Founded in 1797 as the Law Society of Upper Canada (LSUC; ), its name was changed by statu ...

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. In the 1980s, Rosenthal worked with Roach representing 21 peace activists who had been charged in relation to protests against

Litton Industries Litton Industries, Inc., was an American defense contractor that specialized in shipbuilding, aerospace, electronic components, and information technology. The company was founded in 1953 and was named after inventor Charles Litton Sr., who was ...

and their work on manufacturing components for

cruise missiles A cruise missile is an unmanned self-propelled guided missile that sustains flight through aerodynamic lift for most of its flight path. Cruise missiles are designed to deliver a large payload over long distances with high precision. Modern cru ...

, with Rosenthal arguing that Litton executives were endangering the safety of Canadians through its products. Rosenthal was also involved in a campaign to protest an invitation to

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

ambassador Glenn Babb to speak at the

in defence of South African's

apartheid Apartheid ( , especially South African English: , ; , ) was a system of institutionalised racial segregation that existed in South Africa and South West Africa (now Namibia) from 1948 to the early 1990s. It was characterised by an ...

regime. Rosenthal was one of four University of Toronto professors who sought an

injunction An injunction is an equitable remedy in the form of a special court order compelling a party to do or refrain from doing certain acts. It was developed by the English courts of equity but its origins go back to Roman law and the equitable rem ...

to stop Babb along with a declaration by the court that apartheid was a

crime against humanity Crimes against humanity are certain serious crimes committed as part of a large-scale attack against civilians. Unlike war crimes, crimes against humanity can be committed during both peace and war and against a state's own nationals as well as ...

. While this effort was unsuccessful it helped lead to a later decision by the university to divest from South Africa. Roach encouraged Rosenthal to go to law school so that he could represent clients in more serious cases, and he was admitted to

in 1987 at the age of 46. He went on to obtain an LL.B. in 1990 and was called to the Ontario

bar Bar or BAR may refer to: Food and drink * Bar (establishment), selling alcoholic beverages * Candy bar ** Chocolate bar * Protein bar Science and technology * Bar (river morphology), a deposit of sediment * Bar (tropical cyclone), a laye ...

in 1992. Rosenthal joined Roach's firm as a partner. He was a major figure in the Toronto legal community, and was profiled by ''

Toronto Life ''Toronto Life'' is a monthly magazine about entertainment, politics and life in Toronto, Ontario, Canada. ''Toronto Life'' also publishes a number of annual special interest guides about the city, including ''Real Estate'', ''Stylebook'', ''Eati ...

'', ''

The Globe and Mail ''The Globe and Mail'' is a Newspapers in Canada, Canadian newspaper printed in five cities in Western Canada, western and central Canada. With a weekly readership of more than 6 million in 2024, it is Canada's most widely read newspaper on week ...

'', and the

Toronto Star The ''Toronto Star'' is a Canadian English-language broadsheet daily newspaper. It is owned by Toronto Star Newspapers Limited, a subsidiary of Torstar Corporation and part of Torstar's Daily News Brands (Torstar), Daily News Brands division. ...

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 and marginalized clients for free. He was also active in civil law suing police and public officials, and participated in

inquest An inquest is a judicial inquiry in common law jurisdictions, particularly one held to determine the cause of a person's death. Conducted by a judge, jury, or government official, an inquest may or may not require an autopsy carried out by a cor ...

s into the police shootings of several Black men, representing the families of the deceased. Rosenthal represented

Miguel Figueroa Miguel Figueroa (born July 29, 1952) is a Canadian political activist who was the leader of the Communist Party of Canada from 1992 to 2015. He is known for the landmark Figueroa case, which redefined the role of small parties and Canadian Par ...

, the leader of the

Communist Party of Canada The Communist Party of Canada is a federal political party in Canada. Founded in 1921 under conditions of illegality, it is the second oldest active political party in Canada, after the Liberal Party of Canada. Although it does not currentl ...

, in the case Figueroa v. Canada before the

Supreme Court of Canada The Supreme Court of Canada (SCC; , ) is the highest court in the judicial system of Canada. It comprises nine justices, whose decisions are the ultimate application of Canadian law, and grants permission to between 40 and 75 litigants eac ...

. 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. Rosenthal represented many activists who faced charges as a result of political protests, including

Shawn Brant Shawn Brant is a Native activist who lives on the Tyendinaga Mohawk Territory, Ontario, Canada. He has been involved in direct action struggles for Native land rights, in conflict with Ontario provincial authorities. In the 1990s, Brant particip ...

, John Clarke and the

Ontario Coalition Against Poverty The Ontario Coalition Against Poverty (OCAP) was an anti-poverty group in Ontario, Canada, which promoted the interests of the poor and homeless. The group used publicity-generating direct action techniques such as squatting and demonstrations w ...

, Vicki Monague of Stop Dump Site 41,

Dudley Laws Dudley Laws (May 7, 1934March 24, 2011) was a Canadian civil rights activist and executive director of the Black Action Defence Committee. Laws was born in Saint Thomas Parish, Jamaica, to parents Ezekiel and Agatha Laws, and was a brother to si ...

and the Black Action Defence Committee, and Jaggi Singh and others arrested at the 2010 G20 Toronto summit protests, and wrote articles about some of those cases. In 2006, Rosenthal represented Indigenous activists at the

Ipperwash Crisis The Ipperwash Crisis was a dispute over Indigenous land that took place in Ipperwash Provincial Park, Ontario, on September 4, 1995. Several members of the Stoney Point Ojibway band occupied the park to assert claim to nearby land which had be ...

and cross-examined former

Premier of Ontario The premier of Ontario () is the head of government of Ontario. Under the Westminster system, the premier governs with the confidence of a majority the elected Legislative Assembly; as such, the premier typically sits as a member of Provincia ...

Mike Harris Michael Deane Harris (born January 23, 1945) is a retired Canadian politician who served as the 22nd premier of Ontario from 1995 to 2002 and leader of the Progressive Conservative Party of Ontario (PC Party) from 1990 to 2002. Taking the PC ...

over allegedly saying ""I want the fucking Indians out of the park."

Personal life and death

Rosenthal married his first wife, Helen Black (1942–2017), in 1960 when he was 19 and she was 18. Both of them were social activists and would become mathematicians at the University of Toronto. They divorced in 1979, but remained friends. Rosenthal married his second wife, Carol Kitai, a medical doctor, in 1985. Rosenthal was a lifelong

Marxist Marxism is a political philosophy and method of socioeconomic analysis. It uses a dialectical and materialist interpretation of historical development, better known as historical materialism, to analyse class relations, social conflic ...

and political activist. He was a red diaper baby; his mother was active in the

and

anti-war An anti-war movement is a social movement in opposition to one or more nations' decision to start or carry on an armed conflict. The term ''anti-war'' can also refer to pacifism, which is the opposition to all use of military force during conf ...

movements. Rosenthal told the ''

Globe and Mail ''The Globe and Mail'' is a Canadian newspaper printed in five cities in western and central Canada. With a weekly readership of more than 6 million in 2024, it is Canada's most widely read newspaper on weekdays and Saturdays, although it fall ...

'': "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." Rosenthal died in Toronto on May 25, 2024, at the age of 82. He had suffered from

heart disease Cardiovascular disease (CVD) is any disease involving the heart or blood vessels. CVDs constitute a class of diseases that includes: coronary artery diseases (e.g. angina pectoris, angina, myocardial infarction, heart attack), heart failure, ...

and Parkinson’s disease, and died due to complications from

COVID-19 Coronavirus disease 2019 (COVID-19) is a contagious disease caused by the coronavirus SARS-CoV-2. In January 2020, the disease spread worldwide, resulting in the COVID-19 pandemic. The symptoms of COVID‑19 can vary but often include fever ...

. The song "A Little Rain (A Song for Pete)" (2016), by the alternative rock band the

Arkells Arkells is a Canadian rock band, formed in Hamilton, Ontario. In 2006, they signed with Dine Alone Records, and have since signed with Universal Music Canada. They have released nine albums: '' Jackson Square'' (2008), '' Michigan Left'' (2011) ...

, was inspired by Rosenthal. It was written by Arkells' lead singer Max Kerman, a friend of Rosenthal and his family.

Works

* , 2nd edition * * * (with Sheldon Axler and Donald Sarason) editors
''A Glimpse at Hilbert Space Operators''

Birkhäuser Birkhäuser was a Swiss publisher founded in 1879 by Emil Birkhäuser. It was acquired by Springer Science+Business Media in 1985. Today it is an imprint used by two companies in unrelated fields: * Springer continues to publish science (parti ...

, 2010. *

References

{{DEFAULTSORT:Rosenthal, Peter 1941 births 2024 deaths University of Michigan alumni University of Toronto Faculty of Law alumni Academic staff of the University of Toronto Academic staff of the University of Toronto Faculty of Law 20th-century Canadian mathematicians 21st-century Canadian mathematicians Queens College, City University of New York alumni Canadian civil rights lawyers Operator theorists Algebraists Scientists from Queens, New York Canadian Marxists Canadian anti-poverty activists Canadian anti-racism activists Canadian anti–nuclear weapons activists Canadian anti-war activists American anti–Vietnam War activists American civil rights activists American anti–nuclear weapons activists Anti-apartheid activists Canadian Jews Canadian people of Polish-Jewish descent Canadian people of Russian-Jewish descent Canadian people of American-Jewish descent American emigrants to Canada Lawyers in Ontario Deaths from the COVID-19 pandemic in Canada