José-Carlos introduced me to Mario when I visited UNAM in the mid '80's. Mario was just finishing an MA and José-Carlos hoped he could continue towards his PhD at UCSB under my direction. It was immediately clear that Mario's MA thesis was itself of PhD quality, so I was happy to oblige and lucky to be picked. The one worry I did have was that UCSB would not comfortably accommodate such a remarkably talented graduate student, of the sort we so rarely see. Indeed, there were lots of adventures:
Financial support: It would have been a waste for Mario to spend a lot of time working as a TA for low level math courses. To my delight and amazement, this proved unnecessary: one telephone call to Ralph Krause, then the topology czar at NSF, was enough. Once I'd explained the situation he simply said, "tell me what you need and I'll make sure you get it." And he did.
Housing: When he first arrived in Santa Barbara, Mario was, appropriately, dumbfounded by the cost of housing. I believe he told me that his father warned him that it might be some kind of swindle. But soon enough, Mario was able to move into an apartment with a married pair of Chinese graduate students. They all got along fine, and Mario was set.
Poaching: For the only time in my career, other faculty would drop in from time to time, so impressed by Mario that they enthusiastically offered to take him on as a student if Mario ever seemed unhappy working with me. Didn't happen!
Language exams: UCSB required two, typically in French, German or Russian. Mario had no trouble with the French exam, and seemed perfectly willing to try to learn German, but it seemed to me that this would be a waste of time for such a great student. The Department was already having doubts about the point of the exams, so it was not difficult to persuade the graduate committee to let Mario substitute Spanish for German. To make a long story short, Mario's German exam ultimately required him to translate a few pages of his own MA thesis into English, and I (knowing no Spanish) was the grader. He passed, on the first try!
Job Search: After Mario finished all requirements and wrote a brilliant thesis, it was time to find a job. Deep into hiring season I met Mario in the hall and asked if he'd heard anything yet. He showed me a note that he'd gotten a few days earlier, left in his mailbox by a UCSB staff member. It said that a "John Miller" from "Prince-town" was trying to reach him, and left a phone number. I recognized the area code immediately; it was in fact John Milnor calling from Princeton's Institute for Advanced Study, hoping Mario would come work with him!
And so began Mario's mathematical career and the work we now celebrate. So raise a toast to Mario, as he continues his quest of unusual knots and their associated topology!