Joseph Pierre LaSalle (born 28 May 1916 in State College, Pennsylvania; died 7 July 1983 in Little Compton, Rhode Island) was an American mathematician specialising in dynamical systems and responsible for important contributions to stability theory, such as LaSalle's invariance principle which bears his name.
J. P. LaSalle
Joseph Pierre LaSalle
May 28, 1916
State College, Pennsylvania, United States
|Died||July 7, 1983 (aged 67)|
Little Compton, Rhode Island, United States
|Alma mater||California Institute of Technology|
|Institutions||University of Notre Dame,|
Joseph LaSalle defended his Ph.D. thesis on ″Pseudo-Normed Linear Sets over Valued Rings″ at the California Institute of Technology in 1941. In 1946 he joined the Mathematics Department at the University of Notre Dame as an assistant professor and remained there until 1958, becoming a full professor in 1956. During a visit to Princeton in 1947–1948, LaSalle developed a deep interest in differential equations through his interaction with Solomon Lefschetz and Richard Bellman, with whom he developed a close friendship. From 1958 until 1964 LaSalle was based at the Research Institute for Advanced Studies (RIAS) in Baltimore, where he worked closely with Lefschetz and in 1960 published his extension of Lyapunov stability theory, known today as LaSalle's invariance principle.
In 1962-1963 he was President of the Society for Industrial and Applied Mathematics (SIAM) and was a member of its board of trustees in 1964–1967. In 1964 LaSalle founded the Journal of Differential Equations and served as its Editor-in-Chief until 1980. In 1964 he became the first director of the Center for Dynamical Systems at Brown University, where he was also the chairman of the Division of Applied Mathematics in 1968–1973.
Together with J. K. Hale, LaSalle was the recipient of the 1965 Chauvenet Prize for their article, ″Differential Equations: Linearity vs. Nonlinearity″, published in the SIAM Review. In 1975 he was awarded the Guggenheim Fellowship for applied mathematics.