 On the other hand, it is fair to say that Emil Post had in some respects anticipated Gödel’s discoveries. He obtained abstract versions of incompleteness results apparently already in 1922. In particular, he observed that his methods would provide a statement undecidable in Principia Mathematica. These results were, however, based on Post’s own version of the “Church-Turing thesis”, with which he was dissatisfied, and his work was left unpublished. It was reported much later in (Post 1941). 