In this article, we consider the NP-hard problem of two-step colouring a graph. It is required to colour graph in given number colours way, when no pair vertices has same colour, if these are at distance 1 or 2 between each other. The optimum one that uses minimum possible colours.The studied application grid graphs. We four types grids: triangular, square, hexagonal, and octogonal. show hexago...

Currently existing graph grammar-based speciication languages have serious problems with supporting any kind of \speciication-in-the-large" activities. More precisely , they have deeciences with respect to modeling hierarchical data structures or specifying meta activities like manipulation of graph schemata. Furthermore, already proposed graph grammar module concepts are still too abstract to ...

for two normal edge-transitive cayley graphs on groups h and k which have no common direct factor and gcd(jh=h ′j; jz(k)j) = 1 = gcd(jk=k ′j; jz(h)j), we consider four standard products of them and it is proved that only tensor product of factors can be normal edge-transitive.