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Function rings
Abbreviation: FRng
Definition
A function ring (or $f$-ring) is a lattice-ordered ring $\mathbf{F}=\langle F,\vee,\wedge,+,-,0,\cdot\rangle$ such that
$x\wedge y=0$, $z\ge 0\ \Longrightarrow\ x\cdot z\wedge y=0$, $z\cdot x\wedge y=0$
Remark:
Definition
Morphisms
Let $\mathbf{L}$ and $\mathbf{M}$ be $f$-rings. A morphism from $\mathbf{L}$ to $\mathbf{M}$ is a function $f:L\rightarrow M$ that is a homomorphism: $f(x\vee y)=f(x)\vee f(y)$, $f(x\wedge y)=f(x)\wedge f(y)$, $f(x\cdot y)=f(x)\cdot f(y)$, $f(x+y)=f(x)+f(y)$.
Examples
Basic results
The variety of $f$-rings is generated by the class of linearly ordered $\ell$-rings. This means $f$-rings are subdirect products of linearly ordered $\ell$-rings, i.e. $f$-rings are representable $\ell$-rings (see e.g. [G. Birkhoff, Lattice Theory, 1967]).
Properties
Classtype | variety |
---|---|
Equational theory | |
Quasiequational theory | |
First-order theory | |
Congruence distributive | yes, see lattices |
Congruence extension property | |
Congruence n-permutable | yes, $n=2$, see groups |
Congruence regular | yes, see groups |
Congruence uniform | yes, see groups |
Definable principal congruences | |
---|---|
Equationally def. pr. cong. | |
Amalgamation property | |
Strong amalgamation property | |
Epimorphisms are surjective |
Finite members
$\begin{array}{lr} Only the one-element $f$-ring. \end{array}$
Subclasses
Superclasses
References
Trace: » function_rings