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*To*: fom*Subject*: FOM: Feferfest impressions*From*: Stephen G Simpson <simpson@math.psu.edu>*Date*: Tue, 22 Dec 1998 17:52:09 -0500 (EST)*In-Reply-To*: <13952.6450.79150.12327@boole.math.psu.edu>*Organization*: Department of Mathematics, Pennsylvania State University*References*: <13952.6450.79150.12327@boole.math.psu.edu>*Reply-To*: simpson@math.psu.edu*Sender*: owner-fom@math.psu.edu

Stephen G Simpson writes: > In addition, I want to initiate a discussion of the Feferfest, a > recent symposium in honor of Solomon Feferman's 70th birthday, > which I attended. This was a very interesting conference. I had a > lot of fun. Many leading contemporary figures in f.o.m. were > present. Many of the talks were directly relevant to issues that > we have been discussing here on FOM. My talk dealt directly with > an issue that Feferman has returned to many times: predicativity. > Charles Parsons gave an interesting talk on the reasons advanced by > Hilbert and Bernays and others for rejecting the predicativist > program. I will get into these scientific issues in later FOM postings. Right now I want to simply record some impressions of the Feferfest itself. The banquet on Saturday night (December 12, Stanford Faculty Club) was huge, more than 150 people and a lot of after-dinner speeches and testimonials honoring Feferman, who was aglow with all the attention being paid to him. Rick Sommer was the master of ceremonies. Pat Suppes and Anita Feferman gave major speeches. As for the scientific sessions (December 11-13), the level was uneven, but there were a fair number of exciting talks. Between talks, there was not always enough time for questions and discussion, but the session chairmen made a point of inviting Feferman himself to comment on each talk, which he did. The range of Feferman's contributions in f.o.m. is enormous. He has played a huge role in this field. My own talk, entitled `Predicativity: The Outer Limits', went well. I made the point that there is a big difference between Feferman's system IR, explicating predicative provability, and the system ATR0, which explicates predicative reducibility and is of key importance in reverse mathematics. This is despite the fact that IR and ATR0 are proof-theoretically equivalent. Feferman had several comments: (0) He agreed with the distinction I made. (1) He seemed to feel I had not done justice to IR because I didn't go into the motivation in terms of autonomous progressions. (2) He made a point, which I didn't really understand, to the effect that, although each individual theorem of IR is predicative, the whole system is not. (3) He said there is need for systems with a rich type structure explicating predicative provability in that context. I heartily agree with (0) and (3). I plan to write this up in the Feferfest proceedings. Some notable absences from the Feferfest: Gerhard J"ager (absent due to illness), Wilfried Buchholz (last minute change in plans), Harvey Friedman, Georg Kreisel, Paul Cohen, Craig Smorynski. At the Feferfest, Feferman's new book `In the Light of Logic', a collection of essays on f.o.m.), was much in evidence. It can be ordered for 44 dollars from a current Oxford University Press sale catalog, as I did, or by phoning 1-800-451-7556 and mentioning promotion code J375. The sale ends February 28. Speaking of books, I was glad I had a copy of my own new book `Subsystems of Second Order Arithmetic' in hand to show everybody at the Feferfest. Feferman himself had a lot to do with this book, notably as an editor of the Perspectives in Mathematical Logic series. Many Feferfest participants congratulated me on finally publishing this book and/or said that they plan order it. Information about it is available at http://www.math.psu.edu/simpson/sosoa/ I am making some Feferfest information and web links available at http://www.math.psu.edu/simpson/feferfest/ Many Feferfest participants are here on FOM. I urge everyone to join in the discussion. Best wishes to all! -- Steve Name: Stephen G. Simpson Position: Professor of Mathematics Institution: Penn State University Research interest: foundations of mathematics More information: www.math.psu.edu/simpson/

**References**:**Stephen G Simpson**- FOM: Where is Simpson?

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