Abbreviation: DdpAlg
A \emph{distributive dual p-algebra} is a structure $\mathbf{L}=\langle L,\vee ,0,\wedge ,1,^+\rangle $ such that
$\langle L,\vee,0,\wedge,1\rangle $ is a bounded distributive lattices
$x^+$ is the \emph{dual pseudocomplement} of $x$: $x^+\leq y \iff x\vee y=1$
Let $\mathbf{L}$ and $\mathbf{M}$ be distributive dual p-algebras. A morphism from $\mathbf{L}$ to $\mathbf{M}$ is a function $h:L\rightarrow M$ that is a homomorphism:
$h(x\vee y)=h(x)\vee h(y)$, $h(x\wedge y)=h(x)\wedge h(y)$, $h(0)=0 $, $h(1)=1$, $h(x^+)=h(x)^+$
Example 1:
$\begin{array}{lr}
f(1)= &1
f(2)= &1
f(3)= &1
f(4)= &
f(5)= &
f(6)= &
f(7)= &
\end{array}$