Maximally writhed real algebraic links

Oleg Viro introduced an invariant of rigid isotopy for real algebraic knots and links in ${\mathbb{R}\mathbb{P}}^3$ which can be viewed as a first order Vassiliev invariant. In this paper we classify real algebraic links of degree $d$ with the maximal value of this invariant in its two versions: $w$ and $w_{\lambda }$.