Axiom:Ordered Group Axioms
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Definition
An ordered group is an algebraic system $\struct {G, \circ, \preceq}$ which satisfies the following properties:
\((\text {OG} 0)\) | $:$ | Closure | \(\ds \forall a, b \in G:\) | \(\ds a \circ b \in G \) | |||||
\((\text {OG} 1)\) | $:$ | Associativity | \(\ds \forall a, b, c \in G:\) | \(\ds a \circ \paren {b \circ c} = \paren {a \circ b} \circ c \) | |||||
\((\text {OG} 2)\) | $:$ | Identity | \(\ds \exists e \in G: \forall a \in G:\) | \(\ds e \circ a = a = a \circ e \) | |||||
\((\text {OG} 3)\) | $:$ | Inverse | \(\ds \forall a \in G: \exists b \in G:\) | \(\ds a \circ b = e = b \circ a \) | |||||
\((\text {OG} 4)\) | $:$ | Compatibility of $\preceq$ with $\circ$ | \(\ds \forall a, b, c \in G:\) | \(\ds a \preceq b \implies \paren {a \circ c} \preceq \paren {b \circ c} \) | |||||
where $\preceq$ is an ordering | \(\ds a \preceq b \implies \paren {c \circ a} \preceq \paren {c \circ b} \) |
These stipulations can be referred to as the ordered group axioms.