On utilise les variétés LV-M pour construire des compactifications équivariantes d’un groupe avec une variété d’Albanèse nulle mais telles que l’espace des formes holomorphes fermées de degré 1 soit non nul et de dimension inférieure à .
Moduli spaces of vector bundles on families of non-singular curves are usually compactified by considering (slope)semistable bundles on stable curves. Alternatively, one could consider Hilbert-stable curves in Grassmannians. We study some properties of the latter and compare them with similar properties of curves coming from the former compactification. This leads to a new interpretation of the moduli space of (semi)stable torsion-free sheaves on a fixed nodal curve. One can present it as a quotient...
Discuterò una costruzione geometrica, fatta insieme a De Concini, di una modificazione di una configurazione di sottospazi che trasforma i sottospazi in un divisore a incroci normali. Inoltre nel caso di iperpiani questa costruzione è legata alla generalizzazione della equazione di Kniznik-Zamolodchikov ed alla teoria dei nodi, per i sistemi di radici produce dei modelli particolarmente interessati.
On calcule par des méthodes arithmétiques le groupe de Brauer non ramifié des espaces homogènes de groupes algébriques linéaires sur différents corps. Les formules obtenues font intervenir l’hypercohomologie de complexes de groupes de type multiplicatif.
A compact complex space is called complex-symmetric with respect to a subgroup of the group , if each point of is isolated fixed point of an involutive automorphism of . It follows that is almost -homogeneous. After some examples we classify normal complex-symmetric varieties with reductive. It turns out that is a product of a Hermitian symmetric space and a compact torus embedding satisfying some additional conditions. In the smooth case these torus embeddings are classified using...