In Memoriam: Milena Mihail
Milena Mihail, professor emerita of computer science at the UC Irvine Donald Bren School of Information and Computer Sciences (ICS), has passed away after a several-year battle with cancer.
Mihail joined the ICS Computer Science Department in fall 2019.
She earned her Ph.D. in mathematics and computer science from Harvard University in 1989 and a bachelor of engineering from National Technical University of Athens in 1984. Mihail later worked at Bell Labs and Georgia Tech before coming to ICS, where she worked until retiring in 2025.
Mihail made many foundational contributions to the theory of computing throughout her career, with a focus on randomized algorithms, Markov chains, and the analysis of large networks. Her early work, still widely cited today, established the fundamental connection between conductance and mixing time in Markov chains and provided key insights into how simple random walks can efficiently explore complex combinatorial structures such as matroids. She later extended these ideas to massive graphs, studying how random processes behave on large, irregular networks, with implications for search, connectivity, and diffusion. She also contributed to the theory of scale-free networks, helping explain why many real-world systems exhibit heavy-tailed degree distributions and what that implies for robustness and vulnerability.
A recurring theme in her work is the emergence of structure in complex systems. Rather than focusing only on worst-case inputs, she often explored average-case and realistic models, asking how algorithms perform on networks that resemble those observed in practice. This perspective has played an important role in bridging theoretical computer science with fields such as physics, sociology, and biology.
In addition to her research, Mihail played an important role in building interdisciplinary communities, particularly around network science and data-driven modeling. She mentored students and collaborated widely, helping shape a generation of researchers working on large-scale stochastic systems. Many members of the theoretical computer science community have reached out to share how deeply she influenced them. Longtime friend and colleague Costis Daskalakis remembered, “Milena was such a wonderful and warm person, one whose smile and kind nature I will never forget. I am very lucky to have met her.” Dana Randall, who met Mihail at Harvard University and spent many years with her at Georgia Tech, reflected, “Milena was a big influence on me, even from my undergrad days.” Christos Papadimitriou, her undergraduate teacher and later her collaborator, added, “She was inquisitive, persistent, and brilliant, and I learned more things from her than she did from me.”
At UC Irvine, colleagues echoed these sentiments. Sandy Irani, who had known Mihail since her early graduate school days, said, “I will miss Milena’s fierce intelligence and wonderfully dry sense of humor.” Eric Sudderth recalled “fun and thought-provoking conversations” with her, while Ioannis Pangeas, who had known her since his student days, wrote simply, “Milena was the greatest person I met in our field and maybe anywhere.” Tony Givargis, chair of computer science, added: “Those of us who were fortunate enough to know her well remember her warm smile and her thoughtful, perceptive approach to every problem she took on.”
Mihail is survived by her husband Vijay Vazirani, Distinguished Professor of Computer Science at ICS, and son Michel.