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July 9, 1931 - February 4, 2004
Valentina Mikhailovna Borok was born on July 9, 1931, in Kharkov, Ukraine. Her father, Michail Borok, had a PhD in chemistry and was an expert in material science. His genealogy can be traced back to Vilna Gaon. Her mother, Bella Sigal, was an economist. A top student, Bella began graduate school in the early 1920s, but was soon commissioned for a government job. In the early 1930s she held one of the top positions in the ministry of economics of Ukraine. Because of her mother's position, Valentina had a (relatively) privileged early childhood. Yet, as a Jewish woman at such a high position in the government, Bella couldn't possibly have been spared the repressions of the late 1930s. However, unlike most others, she had a remarkable wisdom to foresee what was about to happen and the ability to act on it. In the beginning of 1937, she voluntarily resigned from her position (giving up the many perks that came with it) by citing family reasons, and took instead a low-key job. That saved her and her family. From that time on, Valentina fully shared the hardships of the majority of the population of Ukraine, including the very difficult years of evacuation during World War II.
In 1949, by the advice of her high school teachers, Valentina decided to study mathematics and was admitted as a math student to Kiev State University. There she met and later married a fellow math student, Yakov Zhitomirskii. They were inseparable for the next 54 years. In her second year of undergraduate studies, Valentina (along with Yakov) started research under the supervision of Georgii Shilov, and quickly established herself as a serious player in her area. Her undergraduate thesis on the distribution theory and applications to the theory of systems of linear PDEs was noted as outstanding and published in a top Russian journal. It was later selected (in 1957) for one of the first volumes of the AMS translations. In 1954, Valentina graduated from Kiev University and moved (following G.E. Shilov) to the graduate school at Moscow State University, where she received a PhD in 1957 ["On Systems of Linear Partial Differential Equations with Constant Coefficients"]. From 1960 to 1994 Valentina Borok worked at Kharkov State University. She became a full professor there in 1970, and from 1983 to 1994 she was the Chair of the analysis department.
Starting in the early 1970s, Valentina founded a school on the general theory of PDEs in Kharkov. Her papers lay a foundation for the theory of local and non-local boundary value problems in infinite layers for systems of PDEs. These results have been further developed and extended by her students. One of her earlier important works includes results on the uniqueness and well-posedness of the solutions of the Cauchy problem for evolutionary systems. These results are still being widely cited 40 years later. Valentina also discovered a number of characteristic properties of parabolic and hyperbolic systems. Her other important contributions were in the area of difference, difference-differential, and functional-differential equations. She was, as many believe, the most prominent female mathematician in Ukraine during most of the 1970s and 1980s.
During her lifetime, Valentina published some 80 papers in top Russian and Ukrainian journals. She supervised 16 PhDs and many more master theses. Students started working with her as undergraduates and then continued through graduate school. However, this was not so for several of her students, including some of the very best ones, who were denied entrance to graduate school because of their Jewish nationality. Instead they had to take mandatory post-graduate full-time jobs, leaving little time for research. Valentina continued working with them informally and encouraged them to pursue their research. After their theses were ready, she worked very hard to organize their defenses at universities in other countries of FSU with other formal advisors. Valentina was a true mother figure to all of her students, and was very much involved in and always ready to help with various aspects of their lives.
Valentina Mikhailovna was considered THE teacher of rigorous analysis in Kharkov State University. That was the course in which all the ambitious math students at Kharkov State got their first taste of research through her famous sets of "creative problems," which were required to get an A. She also developed and published original lecture notes on a number of other core courses, as well as more specialized courses, in analysis and PDEs. She established the curriculum and set the tradition that is being actively used more than 30 years later. Valentina Borok was a brilliant lecturer and an extremely dedicated teacher to her undergraduates.
In 1994, a grave illness forced Valentina to urgently retire and emigrate to Israel, as the necessary medical treatment was unavailable in Ukraine. The last ten years she lived in Haifa. She enjoyed very close relationships with her two children, who often sought her advice and wisdom on various aspects of their lives. Her children, Michail Zhitomirskii and Svetlana Jitomirskaya, both became successful research mathematicians. Valentina Borok was actively involved in raising and educating her five grandchildren at all stages of their growth. Her grandchildren ranged in age from 5 months to 24 years at the time of her death in 2004. At least some of them are continuing her legacy.
Photo Credit: Photographs are used with permission of Valentina Borok's family