Howard Jerome Keisler (born 3 December 1936) is an American mathematician, currently professor emeritus at University of Wisconsin–Madison.
His Ph.D. advisor was Alfred Tarski at Berkeley; his dissertation is Ultraproducts and Elementary Classes (1961).
Following Abraham Robinson's work resolving what had long been thought to be inherent logical contradictions in the literal interpretation of Leibniz's notation that Leibniz himself had proposed, that is, interpreting "dx" as literally representing an infinitesimally small quantity, Keisler published Elementary Calculus: An Infinitesimal Approach, a first-year calculus textbook conceptually centered on the use of infinitesimals, rather than the epsilon, delta approach, for developing the calculus.
Several others have gone on to careers in computer science research and product development, including: Michael Benedikt, a professor of computer science at the University of Oxford, Kevin J. Compton, a professor of computer science at the University of Michigan, Curtis Tuckey, a developer of software-based collaboration environments; Joseph Sgro, a neurologist and developer of vision processor hardware and software, and Edward L. Wimmers, a database researcher at IBM Almaden Research Center.
[3] His son Jeffrey Keisler is a Fulbright Distinguished Chair at the University of Massachusetts, Boston, College of Management.