Leqi (Jimmy) Zhu, University of Toronto

On the Space Complexity of Colourless Tasks

Leqi ZhuLeqi (Jimmy) Zhu worked under the supervision of Faith Ellen at the Department of Computer Science at the University of Toronto. He is being recognized for his thesis that comprises some of the most significant research results in the last decade in the area of distributed computing. This is perhaps the most important thesis in the field of distributed computing since the thesis of Jim Aspnes about 27 years ago. It contains several lower bounds to long-standing open problems in Distributed Computing, and introduces several new proof techniques that are certain to have a continuing effect on the field.

Zhu’s interest in studying lower bounds was sparked during his undergraduate studies at the University of Waterloo.

“I was taking a class in algorithms, and the teacher commented to the class that the most interesting open problems in computer science are around lower bounds. When I was applying for grad school, I noticed that Faith was very interested in proving lower bounds, so it sparked my interest.”

An aptitude for computer science

Although his father was a computer science professor in China, he never tried to influence Zhu to pursue computer science.

“I didn’t learn that my father taught parallel computing until I started my PhD. He never pushed it. When we moved from Waterloo to Toronto around the middle grade 10, I signed up for a computer science course. It was my first computer science course, and I didn’t know anything, but there was a test scheduled for my first week of class. So I crammed like crazy and got perfect on the test. That was my first inkling that maybe I had potential for this stuff.”

While working on his undergrad degree, Zhu started to consider working on his PhD after having the opportunity to work at a few different jobs through Waterloo’s co-op program.

“The work was ok, but I didn’t feel challenged, and I didn’t feel like I wanted to do it for the rest of my life. But with math, I always wanted to learn more.”

Future plans for research and teaching

When it came time to choose a topic for his PhD thesis, Zhu followed in the footsteps of his advisor.

“Faith told me about a problem she tried to solve when she was starting out in the field, and it somehow remained open. She made progress with the problem but no one else was able to take it further. It sounded like a natural thing to look into.”

Currently a post doc at the University of Michigan, Zhu is working on randomized algorithms and wants to apply this area of study to distributed computing where randomized algorithms are not really well understood.

“In my PhD, I only considered deterministic algorithms. All the techniques were purely deterministic arguments. It’s a really fruitful and important area to understand what you can do with randomization.”

He is also looking forward to teaching undergrad students and hopes to spark their love of math.

“Teaching is a good way to learn something at a deep level. You truly understand something when you can explain it in a way that others understand it. I also want to students to understand that math is really interesting.”

Recognizing those who have supported his work

When it comes to being recognized for the value of his PhD thesis, Zhu is surprised and honoured by the awards.

“It feels a bit surreal. I’m extremely flattered and honoured.”

He credits his parents, Daniel Zhu and Lisa Yuan for their love and support. He appreciates that his PhD supervisor, Faith Ellen, was able to provide support and keep him humble through the process. He also recognizes his co-author, Rati Gelashvili for being both a mentor and a friend who helped him through many things.

For now, Zhu plans to remain at the University of Michigan working with his supervisor, Seth Pettie.

“I really love living in Michigan. My advisor is brilliant and I’m learning a lot from him. It seems like a good idea to stay longer.”


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