5 papers
The parity of theta characteristics is preserved by infinitesimal deformations
Margarida Mendes Lopes, Rita Pardini, Roberto Pignatelli
In this note, given a family of relative dimension one over a smooth curve, we determine the parity of the restriction of a relative theta characteristic to an arbitrary multiple o…
Surfaces with canonical map of odd degree
Margarida Mendes Lopes, Rita Pardini, Roberto Pignatelli
Let be a smooth complex minimal surface of general type with whose canonical map is generically finite of odd degree onto a surface . We assume t…
Moduli spaces of threefolds on the Noether line
Stephen Coughlan, Yong Hu, Roberto Pignatelli +1
In this paper, we study the moduli spaces of canonical threefolds with any prescribed geometric genus which have the smallest possible canonical volume. This minimal vo…
Birational geometry of the twofold symmetric product of a Hirzebruch surface via secant maps
Marco Andreatta, Ciro Ciliberto, Roberto Pignatelli
In this paper, extending some ideas of Fano, we study the birational geometry of the Hilbert scheme of 0-dimensional subschemes of length 2 of a rational normal scroll. This fourfo…
On canonical threefolds near the Noether line
Roberto Pignatelli
This short note is the extended abstract of a seminar I have delivered on several occasions over the past few months on canonical threefolds whose canonical volume is "close" to th…