# Who was that forgetful mathematician?

Who was the (Japanese?) mathematician who said in a lecture that a certain conjecture still remained to be proved, and one of the students present told him that he (the mathematician) had already proved that conjecture decades earlier?

• Sounds like me once (true story!) about to post a question to SO only to find a "related" question that I'd posted, and answered, 5 years previously – Carl Witthoft Sep 8 '20 at 11:43
• About 1980, after a talk I gave at Berkeley as a post-doc, Professor I. Satake congratulated me on the first theorem that I mentioned. In my lecture I had in fact (correctly) attributed it to him, though maybe didn't write that on the blackboard... I did remind him that he had proven it in 1965. He expressed disbelief... :) – paul garrett Sep 12 '20 at 22:54