Riesz spaceIn mathematics, a Riesz space, lattice-ordered vector space or vector lattice is a partially ordered vector space where the order structure is a lattice. Riesz spaces are named after Frigyes Riesz who first defined them in his 1928 paper Sur la décomposition des opérations fonctionelles linéaires. Riesz spaces have wide-ranging applications. They are important in measure theory, in that important results are special cases of results for Riesz spaces. For example, the Radon–Nikodym theorem follows as a special case of the Freudenthal spectral theorem.
Groupe ordonnéUn groupe ordonné est un groupe muni d'une relation d'ordre respectée par les translations. Soit (G,.) un groupe (la loi du groupe étant notée multiplicativement) et ≤ une relation d'ordre sur G. On dit que celle-ci est compatible avec la loi du groupe lorsque pour tous éléments x, y et z du groupe, la relation x ≤ y entraîne les deux relations zx ≤ zy et xz ≤ yz. Un groupe ordonné est un ensemble muni simultanément d'une loi de groupe et d'une relation d'ordre compatible.
Archimedean ordered vector spaceIn mathematics, specifically in order theory, a binary relation on a vector space over the real or complex numbers is called Archimedean if for all whenever there exists some such that for all positive integers then necessarily An Archimedean (pre)ordered vector space is a (pre)ordered vector space whose order is Archimedean. A preordered vector space is called almost Archimedean if for all whenever there exists a such that for all positive integers then A preordered vector space with an order unit is Archimedean preordered if and only if for all non-negative integers implies Let be an ordered vector space over the reals that is finite-dimensional.
