We know, thanks to Georg Cantor, that the rational numbers --- ratios of integers --- are countable: they can be put into one-to-one correspondence with the natural numbers. How can we make a list that includes all rationals? For the present, let us consider rationals in the interval $latex {[0,1]}&fg=000000$. It would be nice if … Continue reading Listing the Rational Numbers: I. Farey Sequences
Month: September 2018
Tom Lehrer: Comical Musical Mathematical Genius
Tom Lehrer, mathematician, singer, songwriter and satirist, was born in New York ninety years ago. He was active in public performance for about 25 years from 1945 to 1970. He is most renowned for his hilarious satirical songs, many of which he recorded and which are available today on YouTube [see TM147, or search for “thatsmaths” … Continue reading Tom Lehrer: Comical Musical Mathematical Genius
A Trapezoidal Prism on the Serpentine
Walking in Hyde Park recently, I spied what appeared to be a huge red pyramid in the middle of the Serpentine. On closer approach, and with a changing angle of view, it became clear that it was prismatic in shape, composed of numerous barrels in red, blue and purple. An isoceles trapezoidal prism A prism … Continue reading A Trapezoidal Prism on the Serpentine
Face Recognition
As you pass through an airport, you are photographed several times by security systems. Face recognition systems can identify you by comparing your digital image to faces stored in a database. This form of identification is gaining popularity, allowing you to access online banking without a PIN or password. [see TM146, or search for “thatsmaths” at irishtimes.com]. … Continue reading Face Recognition
ThatsMaths 