### Table of Contents

## Semirings

Abbreviation: **SRng**

### Definition

A \emph{semiring} is a structure $\mathbf{S}=\langle S,+,\cdot \rangle $ of type $\langle 2,2\rangle $ such that

$\langle S,\cdot\rangle$ is a semigroup

$\langle S,+\rangle $ is a commutative semigroup

$\cdot$ 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. A morphism from $\mathbf{S}$ to $\mathbf{T}$ is a function $h:S\to T$ that is a homomorphism:

$h(x+y)=h(x)+h(y)$, $h(x\cdot y)=h(x)\cdot h(y)$

### Examples

Example 1:

### Basic results

### Properties

### Finite members

$\begin{array}{lr}
f(1)= &1

f(2)= &10

f(3)= &132

f(4)= &2341

f(5)= &

f(6)= &

\end{array}$