When Robert Sorgenfrey died on January 7, 1996, UCLA lost one of its most devoted sons. Bob entered UCLA as a freshman in 1933 and received his undergraduate degree four years later in mathematics and physics. In 1942, after graduate studies at the University of Texas, followed by a one-year instructorship at Case Institute of Technology, he returned to Westwood as a temporary instructor. He pursued his entire academic career at UCLA, retiring as a full professor in 1979.

Bob's record of contributions to UCLA, both to the campus as a whole and to the Department of Mathematics, is outstanding. Of the many positions he held, both in the Academic Senate and in the College of Letters and Sciences, probably the most challenging was his service as secretary of the Academic Senate during the height of the loyalty-oath controversy. Throughout his long career, university administrators counted on Bob's energy, efficiency, and good sense in a great variety of roles, from secretary of the faculty of Letters and Sciences to a term of service on the Budget Committee, the predecessor the present Committee on Academic Personnel.

Bob played a crucial role in the development of the Department of Mathematics, from the postwar years on. Not long after he joined the faculty, Bob became the department's sole adviser for the department's majors, of which there were already more than one hundred, as well as scheduling officer with the responsibility for assigning faculty to the department's courses. As the department grew, Bob performed these tasks under the formal status of assistant to the chairman and then as the department's first vice chairman.

Bob's administrative talents and intimate knowledge of the details of departmental operations made him the right-hand man of successive department chairs. With Bob being one of the department's most outstanding teachers, it was no surprise when, in 1963, he was the first mathematician to receive the UCLA Distinguished Teaching Award. Immediately after the war, during which there had been very little instruction at the graduate level, Bob and a colleague instituted a highly successful and innovative graduate course in topology. Bob had written his Ph.D. dissertation under R.L. Moore, a topologist as famous for his unusual teaching style as for his great success in training generations of the world's best scholars in that field. The key feature of the “Moore method” is to challenge the students to recreate mathematical discoveries with a minimum of help from the instructor. Bob taught his version of the method in this required graduate course for many years with great success. Later, he developed an undergraduate topology course which, in spite of its reputation as one of the most difficult courses offered by the department, was very popular with the mathematics majors, at least when Bob taught it.

At the lower-division level, Bob had a particular interest in the basic calculus course for students majoring in engineering and the physical sciences. He would generally teach the entire first-year sequence in order and sometimes follow that with the second-year sequence the next year. Students often arranged their entire course schedules quarter by quarter in order to stay with Bob through as much of the calculus sequence as possible. Bob's student following is easy to understand when one reads their evaluations praising his clear, concise lectures enlivened with humor and his deep concern that all his students do their best. His examinations were often characterized as “comprehensive” by the better students and “long” by the less talented, but all emphasized the fairness of his testing and grading.

Bob's interest in teaching extended well beyond his UCLA courses. He played an active role in the Master of Arts in Teaching degree program that prepared graduate students for high school and community college teaching. During the foreign travels that he and his wife, Bernardine, so much enjoyed--where they pursued interests that ranged from fine dining to bird-watching--he made contact with people active in the local secondary education programs. His concern with the teaching of mathematics in high school eventually led him to a very active career as author of successful texts at that level. The range of his activities in mathematics education went all the way from acting as consultant to his publisher on arthmetic texts for elementary-grade students to supervising several Ph.D. students in topology.

Bob's most notable research accomplishment was his discovery of the “Sorgenfrey Line.” In a very brief paper that is considered one of the classics of the topological literature, he solved a problem that had defeated many of the best topologists. Although the real numbers equipped with the half-open interval topology is a normal space, Bob proved by an ingenious argument that its topological product with itself is no longer normal. This example of the failure of a fundamental topological property to be preserved by a basic construction in the subject offers a deep insight into the very nature of topology. Not only did the discovery of the Sorgenfrey Line lead to considerable further research in the foundations of topology, but it has become a permanent part of every mathematics student's topological tool kit.

Aside from his professional career, Bob enjoyed a very active social life with Bernadine and the couple had many good friends. The Sorgenfreys were avid bridge players and enjoyed participating over the years in the UCLA Faculty Women's Club duplicate bridge tournaments. He will be sorely missed by his colleagues and friends both within and outside the mathematics department.

Robert Brown Andrew Comrey Philip Curtis John Garnett

[From University of California In Memoriam, 1996, with correction of the death date from "Jan 6 1995." The date given above comes from the report in AMS *Notices* of October 1996.]

Topological research at UCLA began with the arrival of Robert Sorgenfrey in 1942, soon after he earned a Ph. D. at the University of Texas under the legendary topologist R. L. Moore. High points in the research accomplishments of topologists at UCLA include the solution by Robion Kirby, who was at UCLA from 1965 to 1971, (with Laurence Siebenmann) of four of the seven problems listed by John Milnor in 1963 as the most important in topology at that time. Kirby first presented his famous "torus trick", the key to the solutions, in a UCLA seminar in the summer of 1968. Another of the Milnor problems, the Double Suspension Conjecture was solved by Robert Edwards, who came to UCLA in 1970 and remained here until his retirement in 2006. The accomplishments of Allan Hatcher, who was at UCLA from 1976 until 1984, include the proof of the Smale Conjecture (published in 1983).

About 60 students, supervised by ten advisors, have received Ph. D. degrees from UCLA for dissertations on topological subjects.

[From the History of the UCLA Topology Group, excerpted May, 2013]