[Please distribute.] Fourth Announcement Fields Institute Program on Homotopy Theory and its Applications University of Western Ontario London, Ontario September, 2003 http://jdc.math.uwo.ca/homotopy/ WHAT'S NEW: - The blocks at our hotels will be released on Tuesday, August 19, so book soon! - The schedule has been set and is on the web page. Details: During the month of September, 2003, the Department of Mathematics at the University of Western Ontario will host a program on homotopy theory and its applications to other areas. Gunnar Carlsson, Paul Goerss, Ieke Moerdijk, Jack Morava and Fabien Morel will be in residence for parts of the month. All of the events will take place in London, Ontario. The focus of the month will be a special 5 day version of the Ontario Topology Seminar, beginning on Saturday, September 20 at 9:30 am and ending on Wednesday, September 24 at 4:30 pm. The speakers who have agreed to come are listed below, and a detailed schedule is on the web page. This conference will take place at the London Delta Armouries Hotel in downtown London. In addition, there will be six minicourses at other times during the month given by the five longer-term visitors. Each will consist of two to three lectures. The schedule for these is also on the web page. These courses will take place at the University of Western Ontario. The organizers are Rick Jardine <jardine@uwo.ca> and Dan Christensen <jdc@uwo.ca>. Please contact either one of us with any questions. If you think you might attend, please register online or e-mail one of us. There is no registration fee, but it is important for us to know how many people plan to attend. Hotel and travel information is available on the web page. We recommend you book a hotel room right away, as the conference overlaps with homecoming weekend at Western. We have two blocks which will be released on *August 19*. The conference is supported by the Fields Institute, the NSF, and NSERC. Conference and minicourse speakers, with arrival and departure dates: Adem, Alejandro (Wisconsin) Sep 20 to Sep 28 Baez, John (UC Riverside) Sep 19 to Sep 25 Baum, Paul (Penn State) Sep 19 to Sep 22 Carlsson, Gunnar (Stanford) Sep 14 to Sep 23 Chacholski, Wojtek (Minnesota) Sep 19 to Sep 26 Cisinski, Denis-Charles (Jussieu) Sep 19 to Sep 25 Goerss, Paul (Northwestern) Sep 7 to Sep 13 Grodal, Jesper (Chicago) Sep 19 to Sep 25 Hesselholt, Lars (MIT) Sep 19 to Sep 21 Kapranov, Mikhail (Toronto) Larusson, Finnur (UWO) Sep 7 to Sep 30 Madsen, Ib (Aarhus) May, Peter (Chicago) Sep 21 to Sep 24 Moerdijk, Ieke (Utrecht) Sep 12 to Sep 24 Morava, Jack (Johns Hopkins) Sep 5 to Sep 24 except Sep 11-14 Morel, Fabien (Paris 7) Sep 20 to Oct 4 Snaith, Vic (Southampton) Sep 19 to Sep 30 Strickland, Neil (Sheffield) Sep 19 to Sep 25 Toen, Bertrand (Nice) Sep 20 to Sep 23 Wenger, Thomas (Northwestern) Sep 6 to Sep 23 except Sep 11-15 Currently, 91 people have expressed interest in attending.