The fourth workshop on ``Numerical Ranges and Numerical Radii'' was held on June 1-2, 1998, in conjunction with the Seventh International Linear Algebra Conference, June 3-6, 1998, dedicated to Hans Schneider honoring his retirement. The workshop took place on the ninth floor of Van Vleck Hall of the University of Wisconsin - Madison, which has a magnificent view of beautiful Lake Mendota.

The one and a half day meeting began with an opening remark by the local organizer - Richard Brualdi, who is also the Chair of the mathematics department of University of Wisconsin - Madison. Then fourteen talks were given (for the final program, click here ) in three sessions with coffee breaks sponsored by the International Linear Algebra Society. The meeting ended around noon, June 2, after a closing remark by Hans Schneider.

There were about three dozen participants for the workshop (see the appendix for the complete list) and a workshop photo was taken around noon June 1. Unfortunately, some participants from Europe were not included in the workshop photo due to delayed arrivals caused by the bad weather in New York area on June 1.

Similar to the previous three meetings, participants exhanged many ideas, results and problems on the subject in a very friendly atmosphere. Furthermore, it was announced that there will be a special session on Numerical Range, organized by Pei-Yuan Wu (pywu@cc.nctu.edu.tw), in the ``International Conference on Mathematical Analysis and its Applications 2000'' to be held in Taiwan, January 17 - 21, 2000, and the Fifth workshop on ``Numerical Ranges and Numerical Radii'' will take place in Greece in June of 2000, organized by John Maroulas (maroulas@math.ntua.gr), National Technical University.

Participants:

• T. Ando, Hokusei Gakuen Unvi., ando@hokusei.ac.jp
• A. Berman, Technion, berman@tx.technion.ac.il
• R. Brualdi (organizer), Univ. of Wisconsin - Madison, brualdi@math.wisc.edu
• Olga Azenhas, University of Coimbra, oazenhas@mat.uc.pt
• B. Cain, Iowa State Univ., cain@pollux.math.iastate.edu
• M.T. Chien, Soochow Univ., mtchien@math.math.scu.edu.tw
• C. Davis, Univ. of Toronto, davis@math.toronto.edu
• J. Dias da Silva, Univ. of Lisbon, perdigao@ptmat.lmc.fc.ul.pt
• L.M. DeAlba, Drake Univ., LD9751R@acad.drake.edu
• Antonio Leal Duarte, Univ. of Coimbra, leal@gentzen.mat.uc.pt
• D. Farenick, Univ. of Regina, farenick@abel.math.uregina.ca
• M. Fiedler, Praha, Czechoslovakia
• C.R. Johnson, William and Mary, crjohnso@math.wm.edu
• Yueh-er Kuo, Univ. of Tennessee - Knoxville, KUO@novell.math.utk.edu
• Tom Laffey, University College Belfield, LAFFEY@ollamh.ucd.ie
• C.K. Li (organizer), College of William and Mary, ckli@math.wm.edu
• Raphael Loewy, Technion, loewy@math.technion.ac.il
• John Maroulas, National Technical University, maroulas@math.ntua.gr
• R. McEachin, Univ. of the West Indies
• Dobovisek Mirko, Univ. of Ljubljana, mirko.dobovisek@fmf.uni-lj.si
• H. Nakazato, Hirosaki Unvie., nakahr@cc.hirosaki-u.ac.jp
• K. Okubo, Hokkaido Univ. of Edu., okubo@atson.sap.hokkyodai.ac.jp
• Andre Ran, Vrije Universiteit, ran@cs.vu.nl.
• L. Rodman, William and Mary, lxrodm@math.wm.edu
• H. Schneider, Univ. of Wisconsin - Madison, hans@math.wisc.edu
• Fernando C. Silva, Univ. of Lisbon, fcsilva@ptmat.lmc.fc.ul.pt
• Wasin So, Sam Houston State University, mth_wso@shsu.edu
• I. Spitkovsky, William and Mary, ilya@math.wm.edu
• B.S. Tam, Tamkang Univ., bsm01@hpap.tku.edu.tw
• T.Y. Tam, Auburn Univ., tamtiny@mail.auburn.edu
• P.Y. Wu, National Chiao Tung Univ., pywu@cc.nctu.edu.tw
• David Yopp, Idaho State University, yoppd@howland.isu.edu
• Xingzhi Zhan, Peking Unviersity, zhan@sxx0.math.pku.edu.cn
• Hongding Zhou, University of Regina