MADISON - Susan Beth Horwitz died on June 11, 2014, at Agrace HospiceCare in Fitchburg, seven months after having been diagnosed with stomach cancer (see Throughout the period, her enthusiasm for life, her engagement with friends, and her love for her family shone through. In a final message to her friends, she said, "My bucket list is empty; I go with no major regrets, other than leaving all of you."

Susan is survived by Tom Reps, her husband, with whom she shared her life for 34 years; her mother, Leah of Ithaca, N.Y.; her sisters, Samata of South Falsburg, N.Y., and Amy of Charleston, S.C.; and her brother, David of Arcata, Calif.; along with two nieces and a nephew.

Susan was born on Jan. 6, 1955, in Berkeley, Calif. Her family moved to Syracuse, N.Y., when she was 5, and except for a year in England (1965 to 1966), she spent the rest of her childhood in Syracuse. Susan attended Wesleyan University, and received an A.B. magna cum laude in ethnomusicology in 1977. She became interested in computer science when, on a lark, she accompanied a friend to attend the first lecture of Wesleyan's introductory programming course, found that the instructor "had a delightful smile," and enrolled in the course. She found that she was good at programming, and developed her skills further by working at Wesleyan's recently established Computing Center. After graduation, she worked for Intermetrics, Inc. in Boston and Washington, D.C. for two years before beginning graduate studies in computer science at Cornell University, where she received an M.S. in 1982 and a Ph.D. in 1985.

Susan then joined the Computer Sciences Department at the University of Wisconsin-Madison as an assistant professor. She was promoted to associate professor in 1991 and to professor in 1996. She served as associate chair of the CS Department from 2004 to 2007. She retired and became Professor Emerita in April, 2014. During four separate year-long stays to conduct research abroad, Susan held visiting appointments at L'Institut National de Recherche en Informatique et en Automatique (INRIA) in Rocquencourt, France (1982 to 1983), the University of Copenhagen (1993 to 1994), Consiglio Nazionale delle Ricerche (CNR) in Pisa, Italy (2000 to 2001), and the University of Paris Diderot-Paris 7 (2007 to 2008).

Susan's research expertise was in the fields of Programming Languages and Software Engineering. Among other contributions, her work helped to make the Windows operating system much more stable, starting around 2004. At that time, a group at Microsoft released the SLAM tool, a static program analyzer that checks for bugs in Windows device drivers (which were causing about 85% of the system crashes in Windows). One of the algorithms that makes SLAM successful is the algorithm for interprocedural dataflow analysis that Horwitz and her collaborators developed in 1995.

The quality of Susan's research was recognized with a number of awards. In 1989, she received a Presidential Young Investigator Award from the National Science Foundation. In 2011, she and her co-authors received an ACM SIGSOFT Retrospective Impact Paper Award for their paper "Speeding up slicing," which appeared at the Symposium on Foundations of Software Engineering in 1994. At the time of her death, Susan was highly ranked in two of the twenty-four area-citation rankings for Computer Science compiled by Microsoft Academic Search: in Programming Languages, she was No. 37; in Software Engineering, she was No. 83 (out of over 50,000 and 150,000 researchers, respectively, who have published in those fields).

Susan was a devoted and gifted teacher, known for her imaginative use of props - including nose glasses to explain recursion, and suction-cup-tipped arrows and string to explain pointers - and for composing songs - sung to the tunes of Christmas carols - to drive home the essential points of her lectures. Over the years, she received numerous awards for her teaching, including ones from the UW CS Department (1987 and 1997), the UW CS Student Chapter of the ACM (1989 and 1993), the College of Letters and Science (1992), and the University of Wisconsin (1993).

During the last decade, Susan devoted herself to trying to increase the number of under-represented students (women and targeted minority students) in Computer Science. She was a founding member of the Academic Alliance of the National Center for Women and IT. In 2004, she launched the Wisconsin Emerging Scholars-Computer Science program (WES-CS), which was designed to help attract students at Wisconsin to Computer Science who might otherwise overlook the opportunities that the field offers. The program that she organized is centered around student-led group meetings, at which students work together on interesting problems designed to help them understand and enjoy the topics taught in the introductory programming class. From 2012 to 2014, Susan was the faculty director of Women in Science and Engineering, a UW residential-learning community of about sixty female freshmen. As part of that activity, she organized a weekly seminar for the participants to learn about interesting topics in science and engineering.

Susan kept a good balance between work and other activities: cooking, playing piano, horseback riding, bike riding, yoga, reading, playing poker, and watching movies. She traveled all over the world on horseback excursions, including Iceland, Ireland, Kenya, Portugal, Quebec, Italy, the Pyrenees, the Thar Desert in India, and Mongolia, as well as several trips in the United States. She also enjoyed extended bicycle excursions. In addition to numerous bike trips in Wisconsin, she and her husband biked in Quebec, Vancouver Island, England, Denmark, France, Italy, and the Netherlands - including one memorable trip from London to Didcot during which the flint on the Thames River path caused 13 flat tires in three days!

In recent years, Susan served on the Board of Directors of the Bach Dancing and Dynamite Society, which puts on a three-week chamber-music festival every June, in Madison's Overture Center.

Susan donated her body to science, and at her request there was no funeral. A gathering for her family and friends to commemorate her life will be held this fall. Susan hoped that, in lieu of flowers, any donations in her memory would be directed to either the Susan B. Horwitz WES-CS Endowment at the University of Wisconsin Foundation ( or the Bach Dancing and Dynamite Society (P.O. Box 2348; Madison, WI 53701).

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