Abstract:Abstract. -We investigate the average number of solutions of certain quadratic congruences. As an application, we establish Manin's conjecture for a cubic surface whose singularity type is A 5 + A 1 .
“…As a consequence, our result can be seen as a new record since V is the first example of cubic surface with N = 4 for which Manin's conjecture is proved. Previously, Manin's conjecture was known for only two non-toric cubic surfaces with N = 6 (see [BBD07] and [BD12]) and two cubic surfaces with N = 5 (see [BD09] and [LB11]).…”
Section: Singularity Type Number Of Lines Resultsmentioning
We establish estimates for the number of solutions of certain affine
congruences. These estimates are then used to prove Manin's conjecture for a
cubic surface split over Q and whose singularity type is D_4. This improves on
a result of Browning and answers a problem posed by Tschinkel
“…As a consequence, our result can be seen as a new record since V is the first example of cubic surface with N = 4 for which Manin's conjecture is proved. Previously, Manin's conjecture was known for only two non-toric cubic surfaces with N = 6 (see [BBD07] and [BD12]) and two cubic surfaces with N = 5 (see [BD09] and [LB11]).…”
Section: Singularity Type Number Of Lines Resultsmentioning
We establish estimates for the number of solutions of certain affine
congruences. These estimates are then used to prove Manin's conjecture for a
cubic surface split over Q and whose singularity type is D_4. This improves on
a result of Browning and answers a problem posed by Tschinkel
Ce mémoire de thèse est consacré à l'étude des endomorphismes non inversibles de l'espace projectif complexe P n et plus précisément à leurs sous-espaces totalement invariants (i.e. invariant par image réciproque). Une conjecture énonce que de tels sous-espaces irréductibles de P n sont linéaires ; celle-ci est démontrée pour les diviseurs lisses de P n et pour les diviseurs de P 3 . Cette question est motivée par des enjeux provenant de la dynamique holomorphe mais nous faisons appel aux outils issus de la géométrie algébrique pour y répondre. Soit X un diviseur premier de P n totalement invariant par un endomorphisme non inversible f de P n , on montre dans ce texte les énoncés suivants :(1) le diviseur X contient une courbe de singularités ;(2) le degré d de X est différent de 2 ; et(3) lorsque n = 4 et le diviseur X est normale et non Q-factorielle alors c'est une cubique qui contient un plan linéaire P de P 4 . De plus, si P est Cartier en dehors d'un nombre fini de points alors il est lui-même totalement invariant par une itérée de f . L'étude de la conjecture dans le cas n = 4 nous a mis sur la voie de la deuxième question principale abordée dans ce mémoire de thèse : la classification des cubiques de P 4 à singularités canoniques dont le lieu singulier contient une courbe. Ce résultat constitue la majeure partie de la démonstration du troisième point plus haut.
“…To define the fan Σ, we first define its maximal cones. For example, σ + : > intmat mplus [3][3] = > -3,-3,-2, > 3,0,1, > 0,2,1;…”
Section: Computational Preparationsmentioning
confidence: 99%
“…. , T 5 ] is classically homogeneous of degree 2 with g ′ ∈ T 4 , T 5 , h ∈ T 1 , T 2 , T3 and g defines a smooth conic (30). The smooth Fano threefold X 30 has the Z 2 -graded Cox ring K[T 1 , .…”
We determine the Cox rings of the minimal resolutions of cubic surfaces with
at most rational double points, of blow ups of the projective plane at
non-general configurations of six points and of three dimensional smooth Fano
varieties of Picard numbers one and two.Comment: 34 pages, section two expanded. To appear in Journal of Algebr
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