Template-Type: ReDIF-Paper 1.0 Author-Name: Klaus Nehring Author-Name-First: Klaus Author-Name-Last: Nehring Author-Name: Gordon H. Hanson Author-Name-First: Gordon H. Author-Name-Last: Hanson Author-Name: Humberto G. Llavador Author-Name-First: Humberto G. Author-Name-Last: Llavador Author-Workplace-Name: Department of Economics, University of California Davis Title: A THEORY OF QUALITATIVE SIMILARITY Abstract: The central result of this paper establishes an isomorphism between two types of mathematical structures: ""ternary preorders"" and ""convex topologies."" The former are characterized by reflexivity, symmetry and transitivity conditions, and can be interpreted geometrically as ordered betweenness relations; the latter are defined as intersection-closed families of sets satisfying an ""abstract convexity"" property. A large range of examples is given. As corollaries of the main result we obtain a version of Birkhoff''s representation theorem for finite distributive lattices, and a qualitative version of the representation of ultrametric distances by indexed taxonomic hierarchies. Length: 29 File-URL: https://repec.dss.ucdavis.edu/files/o5HxDtphgKZ4QsobhzGz4U72/97-10.pdf File-Format: application/pdf Number: 85 Classification-JEL: KeyWords: Creation-Date: 20030107 Handle: RePEc:cda:wpaper:85