# Ticket #14271: trac_14271.patch

File trac_14271.patch, 3.7 KB (added by ncohen, 8 years ago)
• ## sage/graphs/generators/smallgraphs.py

# HG changeset patch
# User Nathann Cohen <nathann.cohen@gmail.com>
# Date 1363287649 -3600
diff --git a/sage/graphs/generators/smallgraphs.py b/sage/graphs/generators/smallgraphs.py
 a return graph.Graph(edge_dict, pos=pos_dict, name="Shrikhande graph") def SylvesterGraph(): """ Returns the Sylvester Graph. This graph is obtained from the Hoffman Singleton graph by considering the graph induced by the vertices at distance two from the vertices of an (any) edge. For more information on the Sylvester graph, see _. .. SEEALSO:: * :meth:~sage.graphs.graph_generators.GraphGenerators.HoffmanSingletonGraph. EXAMPLE:: sage: g = graphs.SylvesterGraph(); g Sylvester Graph: Graph on 36 vertices sage: g.order() 36 sage: g.size() 90 sage: g.is_regular(k=5) True """ g = HoffmanSingletonGraph() e = g.edge_iterator(labels = False).next() g.delete_vertices(g.neighbors(e[0]) + g.neighbors(e[1])) g.relabel() g.name("Sylvester Graph") g.set_pos({}) return g def SimsGewirtzGraph(): """ Returns the Sims-Gewirtz Graph. This graph is obtained from the Higman Sims graph by considering the graph induced by the vertices at distance two from the vertices of an (any) edge. It is the only strongly regular graph with parameters v = 56, k = 10, \lambda = 0, \mu = 2 For more information on the Sylvester graph, see _ or its :wikipedia:Wikipedia page . .. SEEALSO:: * :meth:~sage.graphs.graph_generators.GraphGenerators.HigmanSimsGraph. EXAMPLE:: sage: g = graphs.SimsGewirtzGraph(); g Sims-Gewirtz Graph: Graph on 56 vertices sage: g.order() 56 sage: g.size() 280 sage: g.is_strongly_regular(parameters = True) (56, 10, 0, 2) """ g = HigmanSimsGraph() e = g.edge_iterator(labels = False).next() g.delete_vertices(g.neighbors(e[0]) + g.neighbors(e[1])) g.relabel() g.name("Sims-Gewirtz Graph") g.set_pos({}) return g def ThomsenGraph(): """ Returns the Thomsen Graph.
diff --git a/sage/graphs/graph_generators.py b/sage/graphs/graph_generators.py