Plücker formulas for complex plane algebraic curves, relate the genus, number of double points, cusps, inflections and bitangencies. These formulas are almost two hundred years old, but their real analogues for plane curves or surfaces in R4 are from the second half of the last century and later. I will briefly describe the theorem of Fabricius-Bjerre for plane curves and present some of the results and problems in generalising them for surfaces.

## Speaker:

José Basto-Gonçalves

## Institution:

FCUP / CMUP