Jerzy Łoś

Jerzy Maria Michał Łoś (22 March 1920 to 1 June 1998) was a Polish mathematician, logician, economist and philosopher, born in Lwów, then in the Second Polish Republic. He studied in Lviv and Lublin, took his doctorate in 1949 at Wrocław under Jerzy Słupecki, and later held posts at Toruń, the Polish Academy of Sciences and the University of Warsaw. He is especially known for model theory, above all Łoś's theorem on ultraproducts, and for the Łoś-Vaught test and the Łoś-Tarski preservation theorem. His conjecture on the categoricity of countable theories, later proved by Michael Morley and in uncountable form by Saharon Shelah, shaped stability theory. From the 1960s he turned to game theory and mathematical economics. He was a member of the Polish Academy of Sciences from 1983.