D. Computational Tools
To solve the problem of code equivalence computationally, we reduce it to the graph isomorphism problem. For each q-ary code C of length n, we define a labeled coloured graph as follows. The graph contains n copies of the complete graph with q vertices, colored with the first colour. For each codeword, the graph contains a vertex colored with the second color. From a vertex corresponding to codeword c, there is an edge to the vth vertex in the ith complete graph if and only if c has a value v at coordinate i.
