Table of Contents
Semirings with zero
Abbreviation: SRng$_0$
Definition
A \emph{semiring with zero} is a structure $\mathbf{S}=\langle S,+,0,\cdot \rangle $ of type $\langle 2,0,2\rangle $ such that
$\langle S,+,0\rangle $ is a commutative monoid
$\langle S,\cdot\rangle$ is a semigroup
$0$ is a zero for $\cdot$: $0\cdot x=0$, $x\cdot 0=0$
$\cdot$ distributes over $+$: $x\cdot(y+z)=x\cdot y+x\cdot z$, $(y+z)\cdot x=y\cdot x+z\cdot x$
Morphisms
Let $\mathbf{S}$ and $\mathbf{T}$ be semirings with zero. A morphism from $\mathbf{S}$ to $\mathbf{T}$ is a function $h:S\to T$ that is a homomorphism:
$h(x+y)=h(x)+h(y)$, $h(x\cdot y)=h(x)\cdot h(y)$, $h(0)=0$
Examples
Example 1:
Basic results
Properties
Finite members
$\begin{array}{lr}
f(1)= &1
f(2)= &4
f(3)= &22
f(4)= &283
f(5)= &
f(6)= &
\end{array}$