The M1M1 treasure hunt, week 10

"So will you be my personal tutor next term?" asked Ann.
"Alas no," replied the Doctor. I have obtained leave from teaching next term. It is time for me to write some papers, and when that is done, I have every expectation of being promoted."
"You mean you'll become Professor Hu? It doesn't have the same ring to it."
"Maybe not, but can you imagine how frustrating it has been to know some interesting and important mathematical results, but not to be able to tell anyone about them in case it upset the nature of Causality? Now at last the time has come to put pen to paper. So you'll have a new tutor next term.
I hope all goes well for you. I'm sure it will; I happen to know − but no, I mustn't say that. I never find goodbyes easy, so why don't you just leave. Now."

Somewhat surprised by her peremptory dismissal, Ann looked back on her last few eventful weeks, and especially her meetings with younger versions of her lecturers. First there was "M1Ssy," whose precocious preoccupation with combinatorics had led her to the slightly fishy first password

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Then there was the young Russian, whose early experiments with row operations had led to the first half of a characteristic theorem:

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Finally, the Italian, who had directed her to the man with equations in practically every branch of mathematics.

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While she was recalling these names, the blue box bagan to disappear. "Goodbye Doctor," she murmured. "We'll meet again, don't know where, and I certainly don't know when..."