1,764 research outputs found
An obstruction to the strong relative hyperbolicity of a group
No full textWe give a simple combinatorial criterion for a group that,
when satisfied, implies the group cannot be strongly relatively
hyperbolic. Our criterion applies to several classes of groups, such
as surface mapping class groups, Torelli groups, and automorphism
and outer automorphism groups of free groups
The cobordism group of homology cylinders
No full textGaroufalidis and Levine introduced the homology cobordism group of homology cylinders over a surface. This group can be regarded as an enlargement of the mapping class group. Using torsion invariants, we show that the abelianization of this group is infinitely generated provided that the first Betti number of the surface is positive. In particular, this shows that the group is not perfect. This answers questions of Garoufalidis and Levine, and Goda and Sakasai. Furthermore, we show that the abelianization of the group has infinite rank for the case that the surface has more than one boundary component. These results also hold for the homology cylinder analogue of the Torelli group
Weighted Fano varieties and infinitesimal Torelli problem
No full textWe solve the infinitesimal Torelli problem for 3-dimensional quasi-smooth Q-Fano hypersurfaces with at worst terminal singularities. We also find infinite chains of double coverings of increasing dimension which alternatively distribute themselves in examples and counterexamples for the infinitesimal Torelli claim and which share the analogue, and in some cases the same, Hodge-diagram properties as the length 3 Gushel-Mukai chain of prime smooth Fanos of coindex 3 and degree 10
Stefano Torelli
No full textLa voce ricostruisce criticamente la biografia e l'attività artistica del pittore bolognese Stefano Torelli (1704-1780), accompagnandone la carriera nelle varie città europee (Bayreuth, Dresda, Lubecca), fino alla lunga permanenza a San Pietroburgo presso la corte dell'imperatrice Caterina II
Totius iuris celeberrima et difficillima L. Gallus. ff. de liberis & posthumis
No full textsecundùm mentem archetypi Pisano-Florentini, à nobiliss. IC. Laelio Taurello Fanensi explicata ; Ioh. Stekius IC. recensuit & notis locupletavitTitelblatt mit HolzschnittrahmenKolumnentitel: L. Taurelli IC. Enarratio Ad Gallum & L. Vellea
Totius iuris celeberrima et difficillima L. Gallus. ff. de liberis & posthumis
No full textsecundùm mentem archetypi Pisano-Florentini, à nobiliss. IC. Laelio Taurello Fanensi explicata ; Ioh. Stekius IC. recensuit & notis locupletavitTitelblatt mit HolzschnittrahmenKolumnentitel: L. Taurelli IC. Enarratio Ad Gallum & L. Vellea
La pianificazione di area vasta nella l. reg. Emilia-Romagna n. 24/2017 e il Gattopardo
No full textLa pianificazione di area vasta in Emilia-Romagna costituisce un
interessante settore di analisi in ragione di due fattori distinti, ma connessi: la riforma della struttura delle province stabilita dalla l. n. 56/2014 (c.d. “legge Delrio”) e l’adozione della nuova l. reg. n. 24/2017 sul governo del territorio.
La conferma delle funzioni pianificatorie degli enti di area vasta voluta dalla legge Delrio e il contestuale nuovo assetto dell’uso del territorio definito dalla legge regionale consigliano di approfondire il ruolo e le caratteristiche del piano territoriale di area vasta (PTAV), indagandone in particolare la natura strategica o conformativa. Muovendo da questo obiettivo, l’articolo indugia sulle caratteristiche del PTAV e sulle sue (eventuali) difformità rispetto al previgente PTCP, rilevando come i due strumenti siano in realtà più simili di quanto la l. reg. n. 24/2017 voglia far credere, secondo uno schema evolutivo in perfetto stile gattopardesco
Categorical Torelli theorems: results and open problems
No full textWe survey some recent results concerning the so called Categorical Torelli problem. This
is to say how one can reconstruct a smooth projective variety up to isomorphism, by using
the homological properties of special admissible subcategories of the bounded derived cat-
egory of coherent sheaves of such a variety. The focus is on Enriques surfaces, prime Fano
threefolds and cubic fourfolds
On the Torelli theorem for Deligne-Hitchin moduli spaces
No full textArtículos en revistasProbamos un teorema de Torelli para el espacio de moduli de Deligne-Hitchin y lo comparamos con teoremas de Torelli previos para espacios de moduli de Deligne-Hitchin no parabólicos.We prove a Torelli theorem for the parabolic Deligne-Hitchin moduli
space, and compare it with previous Torelli theorems for non-parabolic
Deligne-Hitchin moduli spaces.info:eu-repo/semantics/publishedVersio
On the rank of the flat unitary summand of the Hodge bundle
No full textLet be a non-isotrivial fibred surface. We prove that the
genus , the rank of the unitary summand of the Hodge bundle
and the Clifford index satisfy the inequality . Moreover, we prove that if the general fibre is a plane curve of degree
then the stronger bound holds. In particular,
this provides a strengthening of the bounds of \cite{BGN} and of \cite{FNP}.
The strongholds of our arguments are the deformation techniques developed by
the first author in \cite{Rigid} and by the third author and Pirola in
\cite{PT}, which display here naturally their power and depht.Comment: 19 pages, revised versio
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