Giải bài 3 – Toán quốc tế 2017

Một bài cực khó của kì thi Toán quốc tế 2017 diễn ra tại Rio de Janeiro vào tháng 7 vừa qua. Theo quan sát của một thanh niên an nam thì chỉ có duy nhất một thanh niên nga ngố tên là Mikhail Ivanov giải trọn vẹn bài này trong phòng thi. Thanh niên an nam cũng cố giải, nhưng trong một phòng khác.

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A humble introduction to Machine Learning, Information Extraction, and Bootstrapping Method

Nghia Bui, Saigon, Christmas 2016

Machine Learning

From the beginning days of computers, people have wondered whether computers can be programmed to learn. If we can make them to learn, the effect would be so amazing. For example, ML is frequently used in cancer diagnosis and detection. Cruz and Wishart [CW06] showed that ML methods can be used to substantially (15-25%) improve the accuracy of predicting cancer susceptibility, recurrence and mortality. Indeed, recently [Ng16], it was reported that IBM’s Watson gave proper diagnosis for Japanese leukemia patient after doctors were stumped for months. The supercomputer, sifted through 20 million cancer research papers, was able to find out the proper diagnosis within 10 minutes, and also suggested a new treatment that has since been more effective.

With an undoubted impression about applications of ML, let our discussion continue with the formal definitions and basic concepts of this subfield of computer science.

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The universe is 4D?

This statement:

Little did they know that the universe is four dimensional and even the orbit of planets is an illusion produced when straight motion in a four dimensional space is projected into three dimensions (or something).

immediately reminded me about projective geometry which is one of the most beautiful systems of mathematics.

So the universe is 4D? I don’t know. But if it was true then we could use the concepts of projective geometry to interpret something interesting.

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“Null References: The Billion Dollar Mistake”

Null is clearly evil. We as human tend to forget to check null, and boom … crash!!! Documentation may help, but again we still forget reading documents. Worse, not all documents are correct and up-to-date 100%. Even if we remember to do every null check, our code would be very messy.

So what is the solution?

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