BGU AGENT Spring 2013
Algebraic Geometry and Number Theory Seminar
Department of Mathematics
Ben-Gurion University

Bigraded invariants of real curves

Pedro Ferreira dos Santos
(Tecnico Lisboa)

Wednesdays; April 10, 2013
Room 201


For a smooth projective variety $X$ over $\mathbb{C}$, the Deligne cohomology groups $H_{\mathcal{D}}^p(X;\mathbb{Z}(q))$ form an important set of bigraded invariants. It comes equipped with maps to the singular cohomology $H_{\mathcal{D}}^p(X;\mathbb{Z}(q)) \to H_{\text{sing}}^p(X(\mathbb{C}); (2\pi i)^q\mathbb{Z})$. In a recent work with Paulo Lima-Filho, we have introduced a version of Deligne cohomology with integer coefficients for varieties defined over $\mathbb{R}$. In this theory the role of singular cohomology is played by equivariant cohomology (\emph{w.r.t.} $\mathbb{Z}/2=\text{Gal}(\mathbb{C}/\mathbb{R})$), which is a bigaded cohomology theory. In this talk, we will briefly overview the main properties of these two sets of bigraded invariants for real varieties and describe the ring structures they give for projective smooth real curves.