Bill delivered an interesting keynote lecture "What are Foundations of Geometry and Algebra?"
which you can read about in the abstract and transcript he was so kind to provide
There were also talks (see abstracts) by:
This year marks the 50th anniversary of Lawvere's thesis on algebraic theories and of the far-reaching idea of algebraic structure as a functor adjoint to semantics. Around the time of this important event, Lawvere was also thinking about several other questions in category theory, motivated by his manifold interests from logic to physics, passing through algebra. In fact, so much so, that it was only in 1969 that he made public the open problems arising from his 1963 thesis.
I wish Bill Lawvere all the years in peace and good health that he may need to complete his program.
"Metric spaces, generalized logic and closed categories" and "Taking categories seriously" were two of the most important and useful papers for me in developing a love of category theory, and that his writings and thoughts on category theory in general were hugely influential in my decision to study the subject.
-- Geoff Cruttwell
I want to thank Bill Lawvere as so many of the issues, problems and puzzles that I enjoy working on derive their significance from his rich storehouse of ideas.
-- John Kennison
Congratulations Bill on this 50th anniversary of your work on functorial semantics. When I was a graduate student at Chicago I used to have regular weekly meetings with Saunders Mac Lane. During one of those meetings he said that he had just been on a flight somewhere with Sammy and that Sammy had given him a thesis and asked him to take a look at it and tell him what he (Saunders) thought about it. Now I never did hear what Saunders said to him about it later but I know that the week after he got it he gave me a copy to read. Well I was always getting things to read from Saunders but when he gave me the Functorial Semantics work to read I was immediately struck by the originality and beauty of its construction. Even when I looked at it today as my way of being part of your celebration I felt once again the same sense of amazement at the originality and freshness of that work as I did as a graduate student. I appreciate the work you have done since and all that your students have done to carry on with the spirit of your creations. Best wishes for a great celebration.
-- John MacDonald
It has been well over 40 years since I learned about Bill's thesis and was excited by the beautiful clarifications in it, and soon after met the marvelous worlds of topos theory. In the time since, it has been constantly fascinating to follow Bill's continuing progressive endeavours and a huge privilege even to work with him for a while. He has a profound depth of understanding combined with one of the most creative minds ever to grace the subject of mathematics. What is most inspiring for me is his unwavering commitment to sharing his understanding with others and his ever generous patience in doing so. Algebraic theories and the accompanying foundations were the first great theme in a sequence of bold new ideas that will affect the way we do mathematics for generations. I look forward to following Bill for many years to come.
-- Bob Rosebrugh
I owe the success of my mathematical career to Bill's guidance and inspiration, however, more importantly, I hope I have learned from the example of his openness and generosity with his ideas to become a better teacher. Bill treats every question and conversation with the same attention and earnestness, whether talking to a student or an established colleague.
-- Kimmo Rosenthal
Bill is a true educator -- enthusiastic in explaining matters to others,
keen that they should understand, but also appreciate the beauty of the
material at hand. He shows delight in learning new things, pouring over
interesting papers, listening keenly to talks that capture his
imagination, often engaging the speaker in intense discussion