I study Mathematics as a product of the human mind and not as absolute. – Emil Leon Post Emil Post By: Henry Ouellette Introduction • Emil Leon Post was born on February 11 1897 in the Russian Empire, now called Poland • Post passed away on April 21, 1954 at the age of 57 • Post was born to a Polish-Jewish family, and emigrated from Poland to New York City in 1904. • Post lost his left arm in an accident at the age of 12. This lead him onto the path of mathematics. • Post attended and graduated from Townsend Harris High School, and continued on to the City College of New York, where he graduated in 1917 with a B.S. in Mathematics. • Post would continue on to Columbia University, where he would get his PhD in Mathematics. He did post-doctorate work at Princeton from 1920 to 1921. What did he do? • Emil Post is responsible for the phenomena we study in class! He is the founding father of the Propositional Calculus. • Post also devised truth tables before they were called truth tables! • Post also produced the first Post production system, a system similar to Alan Turing’s Turing Machine. Wrap-Up • Emil Post created the systems that computability experts use daily. He is the third horseman of Computability Theory, along with Alonzo Church and Alan Turing. • Post also helped pioneer recursion theory with his “Post Problem” • This problem entailed that there may exist a recursively enumerable set that cannot be computed. This differs from the Halting Problem because the Turing Degree of the set is less than that of the Halting Problem..