Jerzy Słupecki

He attended the seminar of, and wrote a 1938 doctorate under, Jan Łukasiewicz.

[4][5] Słupecki showed how the many-valued logics of Łukasiewicz could be included in the theory of Post systems, and gave a functionally complete version of the three-valued logic.

[6] In the logic of categorical sentences, he found a rule that made the theory decidable;[7] his work on Aristotle's logic, from 1948, was later reprinted in French.

[8] He also continued the work of Stanisław Leśniewski, and wrote on his system ("protothetics") in 1953, in Studia Logica.

[9][10] A survey, "The Logical Works of Jerzy Slupecki", appeared in Studia Logica XLVIII (1989), by Jan Woleński and Jan Zygmunt.