Return the adjancy matrix of the graph
Return the critical path for a PERT network
If the given graph is not a PERT network, return nul
Return the degree of the given node
Return the incidence matrix of the graph
Return the laplacian matrix of the graph
moore_dijkstra(source, destination)
Return a liste of range
If the returned array include nil values, there is one or more circuits in the graph
Return true if the graph if symmetric, false otherwise
[Validate]