 The above result had been obtained independently by Gentzen (with Bernays), but upon hearing of Gödel’s result Gentzen withdrew his paper from publication. It had also been anticipated by Kolmogorov in his 1925 “On the Principle of the Excluded Middle,” (English translation van Heijenoort 1967) but that paper was largely unknown to logicians who were outside of Kolmogorov’s circle.