Nels David Nelson
Nels David Nelson (January 2, 1918 – August 22, 2003) was an American mathematician and logician. He was born in Cape Girardeau, Missouri, and studied at the University of Wisconsin–Madison, earning his bachelor’s degree in 1939 and his PhD in 1946. His doctoral advisor was Stephen C. Kleene, making Nelson Kleene’s first PhD student. His thesis was "Recursive Functions and Intuitionistic Number Theory," linking intuitionistic logic with recursive function theory.
Nelson taught at Amherst College as an assistant professor from 1942 to 1946. In 1946 he joined The George Washington University in Washington, D.C., as an assistant professor of mathematics, was promoted to full professor in 1958, and served as chair of the Mathematics Department from 1956 to 1967.
His research focused on intuitionistic logic and its connection to recursion. He explored how truth in intuitionistic systems relates to the provability of number-theoretic statements and used the idea of realizability to formalize truth. He showed that some formulas that are classically true cannot be proven in certain intuitionistic systems.
Nelson supervised John Kent Minichiello’s 1967 dissertation "Negationless Intuitionistic Mathematics," and Minichiello won the Ruggles Prize for Mathematics in 1963 under Nelson’s guidance.
Nelson remained at George Washington University until his death in 2003 in Washington, D.C.
This page was last edited on 3 February 2026, at 11:47 (CET).