Abstract:
The article contains a generalization of the classical Whitney formula for the number of double points of a plane curve. This formula is split into a series of equalities, and also extended to curves on a torus, to non-pointed curves, and to wave fronts. All the theorems are given geometric proofs employing logarithmic Gauss-type maps from suitable configuration spaces to $\mathbb C$.
Key words and phrases:Plane curves, Whitney formula, Gauss map, intersection index.