Ruth Aaronson Bari (November 17, 1917 – August 25, 2005) was an American mathematician known for her work in

graph theory In mathematics, graph theory is the study of ''graphs'', which are mathematical structures used to model pairwise relations between objects. A graph in this context is made up of '' vertices'' (also called ''nodes'' or ''points'') which are conne ...

and algebraic

homomorphism In algebra, a homomorphism is a structure-preserving map between two algebraic structures of the same type (such as two groups, two rings, or two vector spaces). The word ''homomorphism'' comes from the Ancient Greek language: () meaning "same" ...

s. She was a professor at

George Washington University , mottoeng = "God is Our Trust" , established = , type = Private federally chartered research university , academic_affiliations = , endowment = $2.8 billion (2022) , preside ...

, beginning in 1966.

Career

The daughter of

Polish-Jewish The history of the Jews in Poland dates back at least 1,000 years. For centuries, Poland was home to the largest and most significant Ashkenazi Jewish community in the world. Poland was a principal center of Jewish culture, because of the lon ...

immigrants to the United States, Ruth Aaronson was born November 17, 1917 and grew up in

Brooklyn Brooklyn () is a borough of New York City, coextensive with Kings County, in the U.S. state of New York. Kings County is the most populous county in the State of New York, and the second-most densely populated county in the United States, be ...

New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...

. She attended

Brooklyn College Brooklyn College is a public university in Brooklyn, Brooklyn, New York. It is part of the City University of New York system and enrolls about 15,000 undergraduate and 2,800 graduate students on a 35-acre campus. Being New York City's first publ ...

, earning her

bachelor's degree A bachelor's degree (from Middle Latin ''baccalaureus'') or baccalaureate (from Modern Latin ''baccalaureatus'') is an undergraduate academic degree awarded by colleges and universities upon completion of a course of study lasting three to six ...

in mathematics in 1939. She earned her

Master of Arts A Master of Arts ( la, Magister Artium or ''Artium Magister''; abbreviated MA, M.A., AM, or A.M.) is the holder of a master's degree awarded by universities in many countries. The degree is usually contrasted with that of Master of Science. Tho ...

degree at

Johns Hopkins University Johns Hopkins University (Johns Hopkins, Hopkins, or JHU) is a private university, private research university in Baltimore, Maryland. Founded in 1876, Johns Hopkins is the oldest research university in the United States and in the western hem ...

in 1943, but had originally enrolled in the doctoral program. When the university suggested that women in the graduate program should give up their fellowships so that men returning from

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

could study, Bari acceded. After marrying Arthur Bari, she spent the next two decades devoted to their family. They had three daughters together. She returned to Johns Hopkins for graduate work, and completed her dissertation on "absolute reducibility of maps of at most 19 regions" in 1966 at the age of 47. Bari's dissertation explored

chromatic polynomial The chromatic polynomial is a graph polynomial studied in algebraic graph theory, a branch of mathematics. It counts the number of graph colorings as a function of the number of colors and was originally defined by George David Birkhoff to study ...

s and the Birkhoff–Lewis conjecture. She determined that, "because of the fact that all other cubic maps with fewer than 20 regions contain at least one absolutely reducible configuration, it follows that the Birkhoff-Lewis conjecture holds for all maps with fewer than 20 regions."Bari, Ruth. Abstract: “Absolute Reducibility of Maps of at Most 19 Regions.” Biographies of Women Mathematicians Her Ph.D. advisor was Daniel Clark Lewis, Jr. and her thesis was titled, ''Absolute Reducibility of Maps of at Most 19 Regions''. After she received her degree, mathematician

William Tutte William Thomas Tutte OC FRS FRSC (; 14 May 1917 – 2 May 2002) was an English and Canadian codebreaker and mathematician. During the Second World War, he made a brilliant and fundamental advance in cryptanalysis of the Lorenz cipher, a majo ...

invited Bari to spend two weeks lecturing on her work in Canada at the

University of Waterloo The University of Waterloo (UWaterloo, UW, or Waterloo) is a public research university with a main campus in Waterloo, Ontario Waterloo is a city in the Canadian province of Ontario. It is one of three cities in the Regional Municipality ...

. Bari's work in the areas of graph theory and homomorphisms—and especially chromatic polynomials—has been recognized as influential. In 1976, two professors relied on computer work to solve the perennial problem of Bari's dissertation, involving the

four-color conjecture In mathematics, the four color theorem, or the four color map theorem, states that no more than four colors are required to color the regions of any map so that no two adjacent regions have the same color. ''Adjacent'' means that two regions sh ...

. When her daughter Martha asked her if she felt cheated by the technological solution, Bari replied, "I’m just grateful that it was solved within my lifetime and that I had the privilege to witness it." During her teaching career, Bari participated in a class-action lawsuit against

which protested inequalities in promotion and pay for female faculty members. The protests were successful. Notable students of Bari include Carol Crawford, Steven Kahn, and Lee Lawrence. Bari retired at the legally mandated age of 70 in 1988 with the distinction of

professor emeritus ''Emeritus'' (; female: ''emerita'') is an adjective used to designate a retired chair, professor, pastor, bishop, pope, director, president, prime minister, rabbi, emperor, or other person who has been "permitted to retain as an honorary title ...

Community and personal life

Bari was active in the

Washington, DC ) , image_skyline = , image_caption = Clockwise from top left: the Washington Monument and Lincoln Memorial on the National Mall, United States Capitol, Logan Circle, Jefferson Memorial, White House, Adams Morgan ...

community. In the early 1970s, Bari used a grant from the

National Science Foundation The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National I ...

to start a master's degree program in teaching mathematics. She felt that math teachers in DC public schools were not as well prepared as they needed to be. Her three daughters became influential in their fields.

Judi Bari Judith Beatrice Bari (1949–1997) was an American environmentalist, feminist, and labor leader, primarily active in Northern California after moving to the state in the mid-1970s. In the 1980s and 1990s, she was the principal organizer of Ear ...

(1949–1997) was a leading labor and environmental activist and feminist, who lived and worked in Northern California. She survived an assassination attempt in 1990.

Gina Kolata Gina Bari Kolata (born February 25, 1948) is an American science journalist, writing for ''The New York Times''. Life and career Kolata was born Gina Bari in Baltimore, Maryland. Her mother, mathematician Ruth Aaronson Bari (1917–2005), was o ...

is a mathematics, health and science journalist for the ''

New York Times ''The New York Times'' (''the Times'', ''NYT'', or the Gray Lady) is a daily newspaper based in New York City with a worldwide readership reported in 2020 to comprise a declining 840,000 paid print subscribers, and a growing 6 million paid d ...

''. Martha Bari is an

art historian Art history is the study of aesthetic objects and visual expression in historical and stylistic context. Traditionally, the discipline of art history emphasized painting, drawing, sculpture, architecture, ceramics and decorative arts; yet today ...

Hood College , motto_lang = la , mottoeng = With Heart and Mind and Hand , established = , type = Private college , religious_affiliation = United Church of Christ , endowment = $104.5 million (2020) , president = Andrea E. Chapd ...

in Fredrick, Maryland. Bari died on August 25, 2005 from complications of

Alzheimer's disease Alzheimer's disease (AD) is a neurodegeneration, neurodegenerative disease that usually starts slowly and progressively worsens. It is the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in short-term me ...

. She had lived in

Silver Spring, Maryland Silver Spring is a census-designated place (CDP) in southeastern Montgomery County, Maryland, United States, near Washington, D.C. Although officially unincorporated, in practice it is an edge city, with a population of 81,015 at the 2020 censu ...

since 1963 and was 87 years old at the time of her death. She was survived by her husband of 64 years of marriage, Arthur Bari (1913–2006). In addition to their three daughters, they had two grandchildren, including Lisa Bari.

References

{{DEFAULTSORT:Bari, Ruth 1917 births 2005 deaths American women mathematicians Jewish American scientists American people of Polish-Jewish descent 20th-century American mathematicians 21st-century American mathematicians George Washington University faculty Graph theorists 20th-century American women scientists 20th-century women mathematicians 21st-century women mathematicians Brooklyn College alumni 21st-century American women