  The aim of this paper is to show that any finite undirected bipartite graph
can be considered as a polynomial $p \in \mathbb{N}[x]$, and any directed
finite bipartite graph can be considered as a polynomial $p\in\mathbb{N}[x,y]$,
and vise verse. We also show that the multiplication in semirings
$\mathbb{N}[x]$, $\mathbb{N}[x,y]$ correspondences to a operations of the
corresponding graphs which looks like a ``perturbed'' products of graphs. As an
application, we give a new point of view to dividing in semirings
$\mathbb{N}[x]$, $\mathbb{N}[x,y]$. Finally, we endow the set of all bipartite
graphs with the Zariski topology.
