John W. Addison Jr. (1930-2025), influential logic professor and UC Berkeley mentor, passed away last summer at age 96. Students remember him for his precise teaching style and elegant notational conventions that shaped generations of logicians. His 1966 model theory course captivated students who arrived with no clear academic direction, setting many on their career paths.

Addison's exams combined intellectual rigor with wit, featuring questions like "This statement is false" that tested deep understanding. He encouraged his PhD students to tackle unsolved problems, guiding them through complex research in areas like the Borel sets and what became known as "Wadge degrees." His approach emphasized analogical reasoning and the use of infinite games to determine complexity.

The author credits Addison with launching their career in computer science after Berkeley, particularly in designing the dataflow language Lucid. Addison's description of continuous functions as "continuously operating Turing machines" directly influenced this work. His generosity extended to introducing students to logic luminaries including Kurt Gödel, Alfred Tarski, Stephen Kleene, and Alonzo Church. Addison's spirit lives on in his academic descendants, particularly through those who now emulate his mentoring style.