# Revision history [back]

### Running Error in my program

In my research I need to find some property of non_commuting graph of a special linear group SL(3,q)

      sage: G=SL(3,4)
sage: G.order()
sage: E=G.list()
sage: Z=G.center()
sage: A=matrix(G.order())
sage: for i in range(G.order()):
for j in range(G.order()):
if E[i]*E[j]<>E[j]*E[i]:
A[i,j]=1
sage: graph=Graph(A
sage: for j in range(G.order()):
if E[i].matrix()==Z[j]:
graph.delete_vertex(i)
sage: I=graph.independent_set()
sage: len(I)
sage: cv=graph.vertexvover()
sage: len(cv)
sage: graph.clique_number()
sage: graph.chromatic_number
`

but I have problem with large data size . How can write these program to avoid the problem .