Dear category theorists, I have received many replies to my previous message, to the list or directly to me. From Prof. Awodey's and Prof. McLarty's messages, I have understood that Prof. Mac Lane's thesis treated a foundational subject on the length of proofs in the context of the Hilbert Program, but he didn't continue this research. And Steve also suggested the recent obituaries more suitable for the source for his bibliographical note and told me that Saunders recently wrote a note about his own thesis, entitled "A late return to a thesis in logic." Prof. Johnstone informed me that it is available in his selected publication volumes. Mr. McGuire gave me an interesting suggestion on translation of the title of CWM. All of these comments are valuable for me. Thank you very much. Hiroyuki Miyoshi 27-May-2005 12:21:49 -0300,1613;000000000000-00000010