Martedi 26 Marzo p.v., alle ore 11.30, presso l'aula Seminari il Prof. Sergey Agafonov (UNESP, Brazil) terrĂ  un seminario dal titolo:
Hexagonal geodesic 3-webs

We prove that a surface carries a hexagonal 3-web of geodesics if and only if the geodesic flow on the surface admits a cubic first integral and show that the system of partial differential equations, governing
metrics on such surfaces, is integrable by generalized hodograph transform method. We present some new local examples of such metrics, discuss known ones, and establish an analogue of the celebrated Graf and Sauer Theorem for Darboux superintegrable metrics.

Ref. Prof. R. Vitolo