Monochromatic configurations on a circle

Gábor Damásdi, Nóra Frankl, János Pach +1

If we two-colour a circle, we can always find an inscribed triangle with angles $(\frac{\pi }{7},\frac{2\pi }{7},\frac{4\pi }{7})$ whose three vertices have the same colour. In fact, Bialosto…