Stanley Tennenbaum
Stanley Tennenbaum was an American mathematician who contributed to the field of logic. In 1959, he published Tennenbaum's theorem, which states that no countable Non-standard [model of arithmetic|nonstandard model] of Peano arithmetic can be recursive, i.e. the operations + and × of a nonstandard model of PA are not recursively definable in the + and × operations of the standard model. He was a professor at Yeshiva University in the 1960s.