# Connexity graph

As a reminder, in graph theory, a graph is a pair G=(V,E).

V={v1, ... , vn} is the set of vertices or nodes.

E={e1, ... , em} is the set of edges or arcs with each element of E is a pair of element of V. For example, e1=( v1, v2).

It is possible to define an oriented graph if you define that the element of E are an oriented pair of vertice.

Here, we just use a simple graph, i. e. without multiple same pair of vertice to define the elements of E and no loop (loop is edge with the same vertice for each element of the pair) .

So, with this definition of graph, we introduce the notion of connexity. The connexity between two vertices is defined by the exitencing of path between these two vertices. A path, in a graph, is a finite or infinite sequence of edges which connect a sequence of vertices.

In connexity graph, we use this concept of connexity just for two adjacent vertices, i. e. two vertices linked by an edge.

More simply, we use the edges two define a relation of connexity between the concept which is modelized by the vertice.

What you should have learned