I gave a talk yesterday on Wednesday about how Laci indirectly and directly affected my early research career. My Ph.D. thesis was on interactive proofs which Laci co-invented in 1985 as Arthur-Merlin games. When I graduated in 1989, I was lucky to get a 2-year position at the University of Chicago, a great theory department with Laci Babai as its star. That 2-year appointment lasted nearly 20 years, much because of the research I did with Laci those first few years.
I wrote four papers with Laci: MIP = NEXP, Arithmetization, Derandomization under worse-case assumptions and Holographic Proofs. These were all exciting papers. MIP = NEXP is surely the most influential paper I had since it led to Probabilistically Checkable Proof Systems.
Even when we didn't co-author, Laci was an invaluable research. My advisor, Mike Sipser, told me his approach to research in complexity: Find the underlying combinatorial problem and solve that problem. I took that a step further: Once I couldn't solve the combinatorial problem I walked down the hall to Laci's office where he could often find a simple trick that gave me what I needed.
Thanks Laci for being my Merlin.