Tribute to Godfried by one of his former Ph.D. students, Jörg-R. Sack

I have the pleasure of being one of Godfried’s “children”. Having arrived at McGill, I was initially
working in a Biomedical Image Processing Lab. Godfried approached me, after I gave a talk in
his Pattern Recognition class, to switch and work on my Ph.D. with him in the then fairly new
field of Computational Geometry. I said that I did not know Geometry well enough to work in
CG. He responded: “neither do many in the field – so don’t worry; the field is young and
exciting”.

I learned a lot from him. He was excellent in collaborating, presenting material, opening new
areas of research, making sound conjectures, having excellent intuition, crafting well-written
papers, and teaching algorithms with skillful illustrations. He loved to teach CG and students
remarked: “You give Godfried any course to teach, he will find a way to teach CG”. At times, in
his classes, he would include incorrect algorithms to reenergize us and would then request
that we find counter-examples. (This included e.g., several wrong linear-time convex hull
algorithms for simple polygons.) I try to maintain his tradition of teaching. His standards were
very high and his graduate students would, at times, be frustrated by his many demands for
stylistic changes to draft papers, but were very happy with the eventual outcome.

He also had tremendous artistic skills incl. a passion for drumming and dancing. His artistic side
also strongly influenced his research in a number of ways: from choice of problems through
crafting of illustrative examples and presentation style.

It was an exciting time for me to be in the CG group at McGill from 79-83. Visitors were
frequent, conferences few, so you were able to meet all the people in the field regularly.
Godfried was a central figure and helped me make life-long connections with now dear
colleagues and friends. I am very grateful also for that.

Thank you for all you have given to me and to the field. You are deeply missed, Godfried!

Jörg

Tribute to Godfried by David Wood

Godfried's influence on my career has been enormous. It can be summarised in one word: Bellairs. Through his Bellairs workshops I did lots of fun research and started numerous collaborations that continue to this day. I have attended workshops organised by numerous world-class researchers, but I still think that Godfried's workshops were the best. He carefully chose the participants always ensuring gender balance (well before it was an obligation to do so); he carefully chose or sometimes invented the research topic (this would take months of work prior to the workshop); and he carefully chose the research problems (with some easier ones to get us motivated, plus some really challenging ones to last the week). It is difficult to replicate this model, because it requires a great amount of skill and work of the organiser. This was no obstacle to Godfried---he was the master. 

Thank you Godfried.

Tribute to Godfried by Joe Mitchell

I can honestly say that if not for the influence of Godfried, I may never have discovered the beauty of computational geometry. As a graduate student at Stanford, in the very early 1980's, I was often standing in the faculty hallway in Terman Engineering, and, there on the orange carpet would be a stack of technical reports from McGill University, just outside George Dantzig's office. Almost all of them were recent papers of David Avis and Godfried Toussaint. I wondered what this topic "computational geometry" was all about, and one evening I carried off a stack of reports to borrow and peruse. I made an immediate connection to the problems Godfried and his collaborators were discussing, as they were very closely related to problems I was discovering in the robotics lab at HRL, where I was working on coding algorithms for route planning. How exciting that there were others blazing a trail in this new area!  I immediately wrote to Godfried at McGill and asked to be put on the mailing list (yes, physical mail) for his technical reports, and I started collecting those red-jacketed reports (all of which I still keep on my shelf). I felt very encouraged by finding this common bond to the "father of computational geometry". 

I met Godfried in person not long afterwards and was immediately taken in by his friendly and enthusiastic encouragement. He invited me to a Bellairs workshop and I came to know him as a colleague, a host, and a friend. Godfried and I had another, less publicly known, connection too, as we both had lived in Oklahoma: he did his BS at the University of Tulsa, and I went to high school in Oklahoma, just north of Tulsa. Surely, though, neither of us would ever claim to be an "Okie"!

Godfried is immortalized in all of the CG classes I teach, as I tell stories about his clever contributions and conjectures, his influence on the establishment of the field, and the ever famous "Godfried's Favorite Polygon"  -- the nonconvex hexagon (pseudotriangle) that all of my students respect for its role in formulating counterexamples.

Each year on this very date I would be writing to Godfried to exchange our annual birthday wishes, both of us sharing the bond of a late July birthday, just one week apart. I surely did not imagine that last year's birthday wishes would be our last such exchanges.

Let me share Godfried's historical reflections he sent me recently when I was researching the early days of the teaching of computational geometry, for the workshop (Educational Forum) we had at SoCG'18.

Godfried wrote of the "early days" of the field:

"I got started doing research on computational geometry in 1974. The CS department (School) was started at McGill in 1971. It was only a graduate school. George Marsaglia was that Head. He was a (the?) world expert on random number generation. Donald Knuth would come and visit us frequently to discuss random number generation with George for inclusion into his next volume.

I was teaching pattern recognition using Duda and Hart’s text which contained many geometric problems without algorithms. Having switched from Electrical Engineering (all my 3 degrees) to CS I thought I should include algorithms in my course. The convex hull seemed like a beautiful place to start. Knuth had the reputation of being an encyclopedia for algorithms. So in 1974 on one of his visits to McGill I asked him if he knew of any convex hull algorithms. He instantly replied that there was one algorithm published in 1972 by Ron Graham. I looked it up, loved it, saw how it could be improved to run faster on the average, and included it in my pattern recognition lectures. So I first started teaching computational geometry in my pattern recognition course in 1974. The amount of CG in the PR course increased rapidly. In the late 70’s David and Vasek Chvatal joined McGill and I learned about the art gallery theorem. I thought of making the guards move, and this started collaborations with David on CG research (visibility) that led to the introduction of the CG courses at around 1980. The exact dates can probably be retrieved from McGill records, as David points out."

I will miss you, dear Godfried. We all miss you.
Joe

Tribute to Godfried Toussaint: Mentor, teacher, advisor, friend by Jit Bose

Mentor, teacher, advisor, colleague, friend. Godfried Toussaint was all of these to me and much more. Godfried was a big influence on my life. Many of the ideals that shape my philosophy/outlook to this day stem from conversations with Godfried. Let me share a few of his thoughts:

"Always share your ideas freely and with everyone. Science is the promotion of knowledge, not the hoarding of knowledge for one's own self-promotion. There will be people who obfuscate or hide their ideas, but try to rise above that and share in the beauty of our field.".

Godfried exemplified this through the initiation of his workshop series in Barbados where groups of researchers were encouraged to work together to solve open problems. Godfried would spend months preparing many interesting research problems that he shared with the group.

"Always err on the side of inclusion when determining co-authorship on a paper. No paper is worth losing a friendship or causing someone pain. There will be people who will try to exclude you for various reasons, but remember, there are so many diamonds out there that you will find many more."

This was also abundantly clear in how Godfried conducted his research. And he helped me through some painful experiences.

"Do not put barriers between yourself and students. Try to learn as much from them as they do from you. Students are not afraid to go down crazy paths that you may discard because of the blinders that experience puts on you. Go down those paths and you may find some diamonds"

Godfried followed me down many crazy paths when I first started my PhD with him. In fact, at McGill, he with Luc Devroye, had instilled a culture where students and professors would have lunch together every day. These informal meetings were the highlight of my days. No barriers. Just a bunch of people who are passionate about research sharing a meal daily. This is an ideal that Godfried was able to transmit to our research group at Carleton.

"Do not just focus on work. Cultivate many other interests and hobbies. It is by diversifying your interests that you will grow and it will come back in many ways to help you."

This for me was best exemplified when Godfried was able to combine his passion for music with his passion for research which gave rise to his book "The Geometry of Musical Rhythm".

Godfried, you opened my eyes and helped guide me through this journey of life. You gave so much to our community, and you gave so much to me. I will miss you dearly, my friend.

-- Jit

Godfried Toussaint ( 1944 - 2019 )

It is with great sadness that we inform you of Godfried Toussaint's sudden passing. Godfried was a pioneer in the field of Computational Geometry. He was a tireless promoter of the beauty of our field. He initiated the Canadian Conference on Computational Geometry (CCCG) and co-founded, with Joseph O'Rourke, the Symposium on Computational Geometry (SoCG). Godfried was renowned for his creativity and making connections between Computational Geometry and other fields. He contributed to such fields  as Pattern Recognition, Image Processing and more recently, Computational Musicology. He was extremely prolific, having published numerous books and articles in these various fields. Godfried was always willing to share his ideas and had a knack for asking beautiful research questions. His passion for research will be missed by all who knew him.

-- Stefan and Jit

For those who would like to post a personal tribute to Godfried can do so by sending their tribute to Stefan Langerman (stefan.langerman@ulb.ac.be) or Jit Bose (jit@scs.carleton.ca) and it will be posted here.