A tribute to Lotfi A. Zadeh

It is indeed a pleasure and honor for me to pay tribute to my dear friend lotfi zadeh on the occasion of his 90th birthday. i first met professor zadeh when i was a doctoral student at columbia university. during the fall of 1989,1 took his course on network theory. he never brought notes to his lectures, which was a demonstration of his mastery of the course, and he was also very attentive to student questions.