Le cône des représentations d’un ordre d’intervalles

Mathématiques et sciences humaines. Mathematics and social sciences

Doignon, Jean-Paul¹  Pauwels, Christophe¹ 

关键词: convex polyhedron;    interval order;    interval ordre representation;   

DOI  :  10.4000/msh.12061

学科分类：数学（综合）

来源: College de France * Ecole des Hautes Etudes en Sciences Sociales (E H E S S)

【 摘 要 】

A fixed, interval order is considered on a finite set of elements. When appropriately defined, its representations form a convex polyhedron. Our results describe the geometricstructure of the polyhedron. The facets are in a one-to-one correspondence with the objects of oneof four types: the minimal elements, the contractible elements as well as the noses and the hollowsof the interval order (the latter notions are inferred from Doignon and Falmagne [1997]). Thepolyhedron has only one vertex, which is the minimal representation (in the meaning of Doignon[1988a]; new properties are established here). All representations thus form a convex cone. Wecharacterize the extreme rays of this cone. The uniqueness of the vertex came as a surprise tous surprise because Balof, Doignon and Fiorini [2012] obtained, for the polyhedron formed by allrepresentations of a semiorder, numerous examples with multiple vertices.

【 授权许可】

Unknown