David Butler and the Prisoner of Alhazen

Once upon a time, I did a PhD in projective geometry. It was all about objects called quadrals (a word I made up) - ovals, ovoids, conics, quadrics and their cones - and the lines associated with them - tangents, secants, external lines, generator lines. During the first two years, I did talks about my PhD research, which I could not resist calling "David Butler and the Philosopher's Cone" and "David Butler and the Chamber of Secants".

At that time, my use of JK Rowling's titles had to stop because there was no suitable mathematical thing to insert into the third title. It's been ten long years since "David Butler and the Chamber of Secants", and finally I have found something to use. Hence, welcome to...

Tagged in Isnt maths cool, One Hundred Factorial, Thoughts about maths thinking