# Archimedean group

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A partially ordered group within which the Archimedean axiom is valid: If \$a^n<b\$ for all integers \$n\$ (\$a\$ and \$b\$ are elements of the Archimedean group), then \$a\$ is the unit of the group (in additive notation: If \$na<b\$ for all integers \$n\$, then \$a=0\$). Totally ordered Archimedean groups may be described as follows (Hölder's theorem): A totally ordered group is Archimedean if and only if it is isomorphic to some subgroup of the additive group of real numbers with the natural order. Thus, the additive group of all real numbers is in a certain sense the largest totally ordered Archimedean group. All lattice ordered Archimedean groups are commutative. Totally ordered groups without non-trivial convex subgroups (cf. Convex subgroup) are Archimedean.

How to Cite This Entry:
Archimedean group. Encyclopedia of Mathematics. URL: http://encyclopediaofmath.org/index.php?title=Archimedean_group&oldid=31539
This article was adapted from an original article by A.I. KokorinV.M. Kopytov (originator), which appeared in Encyclopedia of Mathematics - ISBN 1402006098. See original article