# SageMathCell online https://sagecell.sagemath.org/?q=jlfunsz # (4,4) Moore bound=161; # ''' Main properties of the graph uberti100 | Ord.: 100 / Size: 200 / Diam.: 4 / Avg.dist: 3.32323 / 4-reg.? True / Girth: 6 / Alg.conn. 1.13380 / Domin. number: 23.0 exoo98 | Ord.: 98 / Size: 196 / Diam.: 4 / Avg.dist: 3.27540 / 4-reg.? True / Girth: 6 / Alg.conn. 1.03099 / Domin. number: 22.0 Degree histogram uberti100 : [0, 0, 0, 0, 100] Degree histogram exoo98 : [0, 0, 0, 0, 98] Symmetry properties of the graph uberti100 | Aut.group.ord.: 240 / Cayley ? False --- vtx.trans. ? False -- edge.trans. ? False exoo98 | Aut.group.ord.: 14 / Cayley ? False --- vtx.trans. ? False -- edge.trans. ? False Automorphism group structure C_n is the cyclic group of order n; x means direct product; : means semidirect product. uberti100 : C2 x S5 | center order: 2 exoo98 : C14 | center order: 14 uberti100 distance distrib from vtx. 0: [1, 4, 12, 31, 52] uberti100 distance distrib from vtx. 1: [1, 4, 12, 31, 52] uberti100 distance distrib from vtx. 2: [1, 4, 12, 31, 52] exoo98 distance distrib from vtx. 0: [1, 4, 12, 33, 48] exoo98 distance distrib from vtx. 1: [1, 4, 12, 35, 46] exoo98 distance distrib from vtx. 2: [1, 4, 12, 36, 45] Number of k-cycles for k=3 up to 9 uberti100 0 0 0 90 0 540 1800 exoo98 0 0 0 28 154 546 1624 ''' import networkx as nx uberti100 =Graph(r":~?@c`OA@_gMCd?sRa_yJBwoObPEMC`QNCpUIC@YJCP]KC`aH_GEA_wQD`g]GbxAPchMIawqLbhWbdqQWHXceea]ZFho^fQASGXSagAomgQsngawogq{phA_ohQcpNIWgIbufIQk}fagkNx{jJSAAA@Kr_ocILG?CArU@@Oou__WLLwKFBbaCA?{x`OcOMg?ECRm@@pGqhaefIhwjfqq_JYCmga}bKIOphQaqTdarTtesSDatSTeuSDIvSTLYmDHSUzdRTTqyTDX\mtTVVn") exoo98 =Graph(r":~?@a_GA?_GWD`WUDaoiIaOiEAh?NbwON_O}TDGcScpQODHgX`@eMEWkXfpyRFhs]e`ycGwwbeAMTGycgfQafIIOgjauWJYGlfqurKi[qkRIFJbIwLyGvjB]AIR]|ARqpNJk{a@CwNKGCOYp@lcEBBBL@dPk~`p{yPhWYPGGcLSaBFqUPISPIaA?cbAw~RGshJw_ZKsyQIayBDb`OdrKxcaS|ShosMGs_OdQ`NSM@FA|UhbxA``[iUGCFIwkeMTiA@bAOGRP[apCtdR@BVgoOMhgjNeB") uberti100nx = uberti100.networkx_graph() exoo98nx =exoo98.networkx_graph() # List of graphs to process graphs = [('uberti100 ', uberti100),('exoo98 ', exoo98 )] def count_k_cycles(G, k): count = 0 visited = set() def dfs(path, start, depth): nonlocal count current = path[-1] # Early exit if we?re going too deep if depth == k: if start in G.neighbors(current): # Normalize to avoid duplicates cycle = tuple(sorted(path)) if cycle not in visited: visited.add(cycle) count += 1 return for neighbor in G.neighbors(current): if neighbor not in path and neighbor >= start: dfs(path + [neighbor], start, depth + 1) for v in G.vertices(): dfs([v], v, 1) return count # each cycle counted twice (once forward, once reverse) def algebraic_connectivity(G): """ Compute the algebraic connectivity (Fiedler value) of a graph G. INPUT: - G: a SageMath Graph OUTPUT: - The second-smallest eigenvalue of the Laplacian matrix of G """ L = G.laplacian_matrix() eigenvalues = L.eigenvalues() eigenvalues.sort() if len(eigenvalues) < 2: return 0 # Trivial case: empty or isolated vertex graph return eigenvalues[1] def domination_number(G): """ Compute the domination number of a graph G using MILP. INPUT: - G: a SageMath Graph OUTPUT: - The domination number (integer) """ p = MixedIntegerLinearProgram(maximization=False) x = p.new_variable(binary=True) # Objective: minimize the number of chosen vertices p.set_objective(sum(x[v] for v in G.vertices())) # Constraint: each vertex is dominated for v in G.vertices(): p.add_constraint(x[v] + sum(x[u] for u in G.neighbors(v)) >= 1) return p.solve() # Print properties for each graph in the list print("\n Main properties of the graph\n") for label, graph in graphs: print(f"{label} | Ord.: {graph.order()} / Size: {graph.size()} / Diam.: {graph.diameter()} / Avg.dist: {graph.average_distance().n(digits=6)} / 4-reg.? {graph.is_regular(k=4)} / Girth: {graph.girth()} / Alg.conn. {algebraic_connectivity(graph).n(digits=6)} / Domin. number: {domination_number(graph)} ") print("Degree histogram uberti100 :", nx.degree_histogram(uberti100nx)) print("Degree histogram exoo98 :", nx.degree_histogram(exoo98nx)) print("\n Symmetry properties of the graph\n") for label, graph in graphs: print(f"{label} | Aut.group.ord.: {graph.automorphism_group().order()} / Cayley ? {graph.is_cayley()} --- vtx.trans. ? {graph.is_vertex_transitive()} -- edge.trans. ? {graph.is_edge_transitive()}" ) # automorphism group structure print(" Automorphism group structure") print(' C_n is the cyclic group of order n; x means direct product; : means semidirect product.\n') Auberti100 = uberti100.automorphism_group() print('uberti100 :', Auberti100.structure_description(), ' | center order:',Auberti100.center().order()) Aexoo98 = exoo98.automorphism_group() print('exoo98 :', Aexoo98.structure_description(), ' | center order:',Aexoo98.center().order()) print("\n") ''' print("\n Properties of the graphs as at arXiv\n") for label, graph in nonisographs: print(f"{label} & {graph.average_distance().n(digits=6)} & {graph.girth()} & {algebraic_connectivity(graph).n(digits=6)} & {graph.automorphism_group().order()} \\\\ ") ''' # Compute the distance distribution from a given vertex v in graph G # Returns a list where the i-th element is the number of vertices at distance i from v def distance_distribution(G, v): from collections import Counter distances = G.shortest_path_lengths(v) distribution = Counter(distances.values()) result = [distribution[d] for d in sorted(distribution)] return result print("\n") for label, graph in graphs: print(f"{label} distance distrib from vtx. 0: {distance_distribution(graph, 0)}") print(f"{label} distance distrib from vtx. 1: {distance_distribution(graph, 1)}") print(f"{label} distance distrib from vtx. 2: {distance_distribution(graph, 2)}") # Counting k-cycles for each graph print("\nNumber of k-cycles for k=3 up to 9") for label, graph in graphs: print(f"{label} ", " ".join(str(count_k_cycles(graph, k)) for k in range(3, 10))) print("\n") ''' # from 0 versio Molodtsov  for name, G in graphs: fname = name.strip() + "_adjlst.txt" s = "; ".join( "{}-{}".format(v, ",".join(map(str, G.neighbors(v)))) if G.neighbors(v) else str(v) for v in G.vertices(sort=True) ) with open(fname, "w") as f: f.write(s) # from 0 for label, _ in graphs: base = label.strip() G = globals()[base + "nx"] with open(f"{base}_edges.txt", "w") as f: f.write(",".join( f"{{{u},{v}}}" for u, v in sorted((min(u, v), max(u, v)) for u, v in G.edges()) )) ''' # from 1 for label, _ in graphs: base = label.strip() G = globals()[base + "nx"] with open(f"{base}_Zedges.txt", "w") as f: f.write(",".join( f"{{{u+1},{v+1}}}" for u, v in sorted((min(u, v), max(u, v)) for u, v in G.edges()) )) print("\n DONE \n") ##