## Mathematicians Of The Day

### 20th February

On this day in 1648, a letter from Pierre de Fermat through Frenicle de Bessy to Kenelm Digby reached John Wallis saying that Fermat had solved equations of the type $x^2 - Ay^2 = 1$ for all non-square values up to 150. Thus begins the saga of the mis-naming of Pell's equation.

Click on Ⓟ for a poster.

##### Born:

- 1844: Ludwig Boltzmann Ⓟ
- 1860: Matyáš Lerch Ⓟ
- 1865: Charles Cailler Ⓟ
- 1921: Boris Trakhtenbrot Ⓟ
- 1929: Madan Lal Puri Ⓟ
- 1931: John Milnor Ⓟ

##### Died:

- 1762: Tobias Mayer Ⓟ
- 1778: Laura Bassi Ⓟ
- 1955: Arthur Lee Dixon Ⓟ

#### Quotation of the day

##### From Ludwig Boltzmann

The most ordinary things are to philosophy a source of insoluble puzzles. With infinite ingenuity it constructs a concept of space or time and then finds it absolutely impossible that there be objects in this space or that processes occur during this time... the source of this kind of logic lies in excessive confidence in the so-called laws of thought.