Prof. Andrej Bogdanov

#23 WS Teacher’s Message

Dear students,

Alice claims to Bob that the coffee at the (now unfortunately closed) Tolo Cafe at her Lee Woo Sing College is much better than the one at the 330 cafe across campus. Bob doesn’t believe that Alice knows a thing about coffee. To test her skill, Bob buys a coffee drink from one of the two places, pours it in an unmarked cup, and asks Alice to tell him where it came from. If Alice guessed correctly perhaps she just got lucky. But perhaps Alice really is the coffee expert that she claims to be.

This silly game in which Alice proves her coffee mastery to Bob is not so different from what happens when you log into your facebook account and “prove” to Facebook that you should be allowed to read your posts. The security of your internet logins was invented well before there was a Facebook, an iPhone, or even an internet. It came out of the minds of some young, not particularly experienced computer scientists who were brave enough to dream up what the future would look like by having some very unusual ideas.

I have been teaching computer science at CUHK ever since I moved to Hong Kong in 2008, when there was no 330 cafe and no Tolo Cafe. This was bad news for a passionate coffee drinker like me. Lee Woo Sing College existed only in the imagination of our founder. Some great things like our college can only happen through the long-term dedicated work of many people: the college master, the staff, the students, the teachers. Others, like the internet login, did not take up any expensive equipment or endless hours of toil. They were the products of curious minds wandering in unexpected directions.

Once when I was stuck on a math problem in college my teacher told me that there are not so many ideas to try. One should simply have the courage to try them all. In these times when some of us are unable to visit our families and friends, our minds can luckily still wander on interesting journeys from one idea to the next. Most will disappear in a puff of smoke, but every once in a while we will end up in a new and interesting place.

About Prof Andrej Bogdanov: Associate professor of Department Computer Science and Engineering, joined Lee Woo Sing College in 2009. He is interested in pseudorandomness, one-way functions, property testing and discrete probability. If you would like to know more about Prof Bogdanov, please visit http://www.cse.cuhk.edu.hk/~andrejb/

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