Table of Contents

Pocrims

Abbreviation: Pocrim

Definition

A \emph{pocrim} (short for \emph{partially ordered commutative residuated integral monoid}) is a structure $\mathbf{A}=\langle A,\oplus,\ominus,0\rangle$ of type $\langle 2,2,0\rangle$ such that

(1): $((x \ominus y) \ominus (x \ominus z)) \ominus (z \ominus y) = 0$

(2): $x \ominus 0 = x$

(3): $0 \ominus x = 0$

(4): $(x \ominus y) \ominus z = x \ominus (z \oplus y)$

(5): $x \ominus y = y \ominus x = 0 \Longrightarrow x=y$

Morphisms

Let $\mathbf{A}$ and $\mathbf{B}$ be pocrims. A morphism from $\mathbf{A}$ to $\mathbf{B}$ is a function $h:A\rightarrow B$ that is a homomorphism: $h(x \oplus y)=h(x) \oplus h(y)$, $h(x \ominus y)=h(x) \ominus h(y)$, $h(0)=0$.

Definition

A \emph{pocrim} is a structure $\mathbf{A}=\langle A,\oplus,\ominus,0\rangle$ such that

$\langle A,\ominus,0\rangle$ is a BCK-algebra

$(x \ominus y) \ominus z = x \ominus (z \oplus y)$

Examples

Example 1:

Basic results

Properties

Feel free to add or delete properties from this list. The list below may contain properties that are not relevant to the class that is being described.

Finite members

1,1,2,7,26,129

$\begin{array}{lr}

f(1)= &1\\
f(2)= &1\\
f(3)= &2\\
f(4)= &7\\
f(5)= &26\\

\end{array}$ $\begin{array}{lr}

f(6)= &129\\
f(7)= &\\
f(8)= &\\
f(9)= &\\
f(10)= &\\

\end{array}$

Subclasses

Hoops

Superclasses

Polrims

Commutative residuated partially ordered monoids

BCK-algebras reduced type

References


1) D. Higgs, \emph{Dually residuated commutative monoids with identity element as least element do not form an equational class}, Math. Japon., \textbf{29}, 1984, no. 1, 69–75 MRreview