I am taking a course about Hilbert Spaces this semester. A very basic notion in a Hilbert Space is that of the norm. For a while now, I kept several questions regarding norms in the back of my mind, and as I finally got to think about them, I wanted to share my conclusions with you.
Yesterday, Zohar Gilboa, with whom I take a PDE course, asked me the following riddle. I must admit it is probably the riddle I like the least on my site thus far. It is very easy though, and as Zohar told me he really liked it himself, I decided to publish it anyways.
This article is the first among a series of articles describing the subject of Secure Computing. The material was mainly taken from a Cryptography course by Amos Fiat.
In 1998 (I can’t believe it was so long ago!) I was working at MATE (Media Access Technologies), an Israeli start-up at the time, specialising in face recognition and video searching. It was then that I came to know one of the coolest tricks in image recognition - the Hough Transform (pronounced “huf transform“).
You write down 2 numbers on 2 pieces of paper (one number on each piece). You put each paper in a sealed envelope. I choose one of the envelopes randomly and open it. I then carry out a certain procedure at the end of which I know with a probability greater than 1/2 whether I received the larger or the smaller of the numbers. I can do this even if when you initially wrote down the numbers, you knew my decision procedure!
How can I do that? What is my trick?
