No description available.

This paper aims at presenting the necessary tools to prove that a scheme of finite type over Z exhibits the same singularities as those which occur on a Grassmann variety. First, basic theory regarding the combinatorial objects matroids is presented. Some important examples for the remainder of the paper are given, which also serve to aid the reader in intuition and understanding of matroids. Basic algebraic geometry is presented, and the building blocks affine varieties, projective varieties and general varieties are introduced. These object are generalised in the following subsection as affine schemes and schemes, which are the central object of study in modern algebraic geometry. Important results from the theory of algebraic groups are shown in order to better understand the formulation and proof of the Gelfand–MacPherson theorem, which in turn is utilised, together with Mnëv’s universality theorem, to prove the main result of the paper.

Les grassmanniennes symplectiques impaires sont une famille d'espaces quasi-homogènes très proches des grassmanniennes symplectiques de par leur construction et leurs propriétés. Dans ce travail, j'étudie leur cohomologie classique et quantique. Pour les grassmanniennes symplectiques impaires de droites, j'obtiens une règle de Pieri quantique ainsi qu'une présentation de l'anneau de cohomologie quantique. J'en déduis la semi-simplicité de cet anneau et je détermine une collection exceptionnelle complète pour la catégorie dérivée, ce qui me permet de vérifier pour cet exemple une conjecture de Dubrovin. Dans le cas général, je démontre un principe quantique-classique pour certains invariants de Gromov-Witten de degré un. Sous réserve de l'énumérativité des invariants de degré supérieur, je prouve que la règle de Pieri quantique est entièrement déterminée par le calcul des invariants de degré un. / Odd symplectic Grassmannians are a family of quasi-homogeneous spaces that are closely related to symplectic Grassmannians by their construction and properties. The goal of this work is to study their classical and quantum cohomology. For odd symplectic Grassmannians of lines, I obtain a quantum Pieri rule and a presentation of the quantum cohomology ring. I prove the semisimplicity of this ring and determine a full exceptional collection for the derived category, which enables me to check a conjecture of Dubrovin in this example. In the general case, I prove a quantum-to-classical principle for some degree one Gromov-Witten invariants. Assuming higher-dimensional Gromov-Witten invariants are enumerative, I conclude that the quantum Pieri rule is entirely determined by the knowledge of degree one invariants.