## Mathematicians Of The Day

### 8th November

On this day in 1824, János Bolyai wrote to Franz Taurinus

The assumption that the sum of the three angles of a triangle is less than 180° leads to a curious geometry, quite different from ours [i.e. Euclidean geometry] but thoroughly consistent, which I have developed to my entire satisfaction, so that I can solve every problem in it excepting the determination of a constant, which cannot be fixed a priori. .... the three angles of a triangle become as small as one wishes, if only the sides are taken large enough, yet the area of the triangle can never exceed, or even attain a certain limit, regardless of how great the sides are.On this day in 2011 Google released a Halley doodle.

Click on Ⓟ for a poster.

##### Born:

- 1656: Edmond Halley Ⓟ
- 1843: Moritz Pasch Ⓟ
- 1846: Eugenio Bertini Ⓟ
- 1848: Gottlob Frege Ⓟ
- 1854: Johannes Robert Rydberg Ⓟ
- 1868: Felix Hausdorff Ⓟ
- 1904: William Edge Ⓟ
- 1912: Elgy Johnson Ⓟ
- 1914: George Dantzig Ⓟ
- 1919: Leopold Schmetterer Ⓟ

##### Died:

- 1633: Xu Guang-qi Ⓟ
- 1719: Michel Rolle
- 1832: Amélie Harlay Ⓟ
- 1858: George Peacock Ⓟ
- 1940: Andrei Petrovich Kiselev Ⓟ
- 1952: Gino Fano Ⓟ
- 1992: Tatsujiro Shimizu Ⓟ
- 2001: Albrecht Fröhlich Ⓟ

#### Quotation of the day

##### From Gottlob Frege

Arithmetic has begun to totter.