Answer:
A graph is a collection of set of edges E and vertices V, where each edge joins pair of vertices.
A graph is undirected when the edges has no direction.
A graph is directed when the edges has confined direction.
An edge is directed if it is defined to come out from one vertex and goes to another fixed vertex.
A loop is an edge from a vertex to itself.
A path from a vertex x to another vertex y is a sequence of distinct edges that joins sequence of distinct vertices:
(x,[tex]x_{1}[/tex])→([tex]x_{1}[/tex], [tex]x_{2}[/tex])→([tex]x_{2}[/tex], [tex]x_{i}[/tex])→ .... → ([tex]x_{j}[/tex],y)
A cycle is path that starts and ends at same vertex.
A circuit is a path that starts and ends at same vertex, but not necessarily contain distinct vertices.
An Euler circuit is circuit that traverse each edge of the graph exactly once and covers all vertices.
An Hamiltonian circuit is a simple circuit that traverse each vertex of the graph exactly once and covers all edges.
Degree of a vertex is the number of edges incident on it.
Explanation:
