Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

Preface 1. Polarity 2. Conics and quadrics 3. Plane cubics 4. Determinantal equations 5. Theta characteristics 6. Plane quartics 7. Cremona transformations 8. Del Pezzo surfaces 9. Cubic surfaces 10. Geometry of lines Bibliography Index.

Classical Algebraic Geometry: A Modern View

New results on overlap and grouping functions

Homaloidal hypersurfaces and hypersurfaces with vanishing Hessian

A characteristic-free criterion of birationality

On montre que tout ensemble de generateurs du groupe de Cremona de l'espace projectif de dimension plus grande que 2 doit contenir un nombre infini non denombrable de transformations non triviales.

Une remarque sur la génération du groupe de Cremona

Nous classifions les transformations birationnelles quadratiques de l'espace projectif complexe de dimension trois, a des isomorphismes lineaires pres. Elles sont de trois sortes, selon que le degre de leur inverse est 2, 3 ou 4. Il y a en tout 30 types differents; en 1871, L. Cremona en avait deja decrit 23.

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Transformations birationnelles quadratiques de l’espace projectif complexe à trois dimensions

We construct the Cremona transformations of Pn satisfying the following property: there exist P1, P2 ∈ Pn such that the image of all straight lines through P1 are straight lines through P2. We characterise these transformations, and for all non-negative integer d we give a formula for the dimension of the set of those whose degree is d.

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Les transformations de Cremona stellaires

We describe the group structure of monomial Cremona transformations. It follows that every element of this group is a product of quadratic monomial transformations, and geometric descriptions in terms of fans.

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On the monomial birational maps of the projective space

We consider Cremona Transformations on Open image in new window, whose base locus schemes are double Fossum-Ferrand structures supported on a smooth, irreducible positive dimensional subvariety. We show that if the codimension of the base locus is 2 or if its dimension is no greater than Open image in new window, then N=3 and such a transformation is a Cubo-Cubic Cremona Transformation not defined along a twisted cubic curve. We also prove that the same conclusion holds for such Cremona Transformations either assuming Hartshorne Conjecture on Complete Intersections or that they are defined by degree three homogeneous polynomials.

Ivan Pan

Papers

Une remarque sur la génération du groupe de Cremona

Transformations birationnelles quadratiques de l’espace projectif complexe à trois dimensions

Les transformations de Cremona stellaires

On the monomial birational maps of the projective space

Cremona transformations and special double structures