Hello! Does anybody sees where is the probleme with this code: # Weights w and parameter B are given def MinDiameterSpanningSubgraph(G, B): # ILP returns minimum diameter in a spanning subgraph I = MixedIntegerLinearProgram(maximization = False) # This part tells us if the edge uv is in subgraph G' x = I.new_variable(binary = True) # y[uv,ij] = 1,if the edge ij is on path from u to v y = I.new_variable(binary = True) # b[uv,k] = 1 if k is in the path from u to v b = I.new_variable(binary = True) d = I.new_variable() I.set_objective(d[0]) # Edge uv is labeled with Set( [u,v]) if u and v are adjacent I.add_constraint( sum( x[ Set([u,v]) ]* w for u,v,w in G.edges()) <= B) for u,v in Combinations(G,2): for i,j in G.edges(labels=false): I.add_constraint( y[ (Set([u,v]), Set([i,j])) ] <= x[ Set([i,j]) ]) # Sum of the the adjacent vertexes to u = u', that are on the path to v equals 1 I.add_constraint( sum (y[ ( Set([u,v]), Set([u,j])) ] for j in G[u]) == 1) # Sum of the the adjacent vertexes to v =v', that are on the path to u equals 1 I.add_constraint( sum (y[ ( Set([u,v]), Set([v,j])) ] for j in G[v]) == 1) for k in set(G) - set([u,v]): # If vertex is on the path from u to v, the number of edges from the vertex has to be 2, otherwise is 0 and it means the vertex is not on the path I.add_constraint ( sum( y[ (Set([u,v]), Set([k,l]) )] for l in G[k]) == 2*b[Set([u,v]),k]) # d is the longest distance in graph I.add_constraint( d[0] >= sum( y[(Set([u,v]), Set([i,j]))] for i,j in G.edges(labels=false)) ) return I,x
#za G(n,r) for k in [4]: number = 2^k data = 'points-'+str(number)+'.txt' for r in [0.7]: G = Graph() for line in open(data): x,y = line.split(' ') G.add_vertex( (float(x), float(y)) ) for x,y in Combinations(G, 2): if sqrt ( (x[0]-y[0])^2 + (x[1]-y[1])^2) <= r: G.add_edge(x,y) print G P=MinDiameterSpanningSubgraph(G, 0.8 * len(G.edges())) print 'Pisem za k in r', k , r P.write_lp('MinDiameterSpanningSubgraph-' + str(number) + '-' +str(r) + '-G(n,r)') I get the same error for every k and r I try. Thank you for your help! -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at https://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.