Get to know Roei Tell, assistant professor, who joined the Department of Computer and Mathematical Sciences (University of Toronto Scarborough) and the tri-campus graduate Department of Computer Science in August 2023.

Tell received his PhD in 2020 at The Weizmann Institute of Science, Department of Computer Science and Applied Mathematics. Before coming to U of T, he held postdoctoral positions at MIT and at the Institute for Advanced Study and DIMACS.

What attracted you to your specific area of research in computer science?

The fundamental questions that are asked, and the stunningly rich intellectual activity put in to answer them! The digital revolution brought certain universal human questions to the forefront of science. For example: How efficiently can algorithmic procedures perform tasks? How do limited resources impose constraints? And can things that appear real substitute the real thing? Theoretical Computer Science is a rapidly evolving discipline that studies these questions in their utmost generality, with precision and rigor. I love studying such fascinating universal and general questions, and I love the brilliant ideas in the discipline, synthesizing a wide array of tools from computer science, mathematics and many other areas of science.

Tell us about some of the key questions you’re looking to answer through your research in computational complexity theory, and the possible practical applications of your work.

Resources in our world are always in shortage. I study the limits of resource-efficient computation: What can algorithms achieve when time and other resources are limited, and more importantly, what can’t they achieve? Can we delineate the boundary of efficient computation, and can we leverage certain limitations to our advantage (e.g., by understanding the limitations of malicious agents)? My core interest is in algorithmic randomness, and in particular in the difference between algorithmic settings in which randomness is inherent, and settings in which randomness can be efficiently simulated. Starting from this core question, I branch out to study many areas in theoretical computer science, such as complexity theory, lower bounds, algorithms, cryptography, interactive protocols, and more.

What’s one thing you hope students who study or work with you will come away with?

My goal is to help students develop as researchers, as scientists and as members of the scientific community. At U of T, we can provide students with the freedom and the resources to explore their intellectual interests and develop their long-term scientific agenda. I’d like my students to find their passion inside theoretical computer science — there are more than enough challenges to be fascinated by — and pave a path to enjoy contributing to the discipline.

What drew you to the Department of Computer Science at the University of Toronto?

The CS department at U of T is a major place for theoretical computer science, as the birthplace of one of the most important open problems — driving research in the discipline — the P vs. NP problem (this problem was introduced here by Stephen Cook, and also independently in Russia by Leonid Levin, in times where global scientific cooperation was more limited). We have a large, strong and diverse theory group, with faculty and students doing cutting-edge research across many areas: algorithms, complexity theory, cryptography, differential privacy, discrepancy theory, distributed computing, game theory, graph theory, quantum computation and more.

How are you finding life in Toronto so far and what are you looking forward to doing or experiencing in the city?

I love the social atmosphere in the city, and in particular the relative emphasis on diversity, inclusiveness and tolerance. It’s amazing for me that most people living here are immigrants like me, originally born outside Canada; this creates a welcoming and tolerant environment and makes it easy to connect with others. I also love the booming energies of a huge city, with an exploding cultural scene and food scene.

What do you enjoy doing outside of your work as a computer scientist?

My wife and I have been greatly enjoying the city and the new people we’re meeting. We’ve been exploring food, dance, movies, theatre, festivals, cafes, etc. I love walking around the park next to my home, meeting new friends, going to farmers’ markets and bicycling around the city.