Matches in DBpedia 2015-10 for { ?s ?p "In the mathematical field of graph theory, the Errera graph is a graph with 17 vertices and 45 edges discovered by Alfred Errera. Published in 1921, it provides an example of how Kempe's proof of the four color theorem cannot work.Later, the Fritsch graph and Soifer graph provide two smaller counterexamples.The Errera graph is planar and has chromatic number 4, chromatic index 6, radius 3, diameter 4 and girth 3. All its vertices are of degree 5 or 6 and it is a 5-vertex-connected graph and a 5-edge-connected graph."@en }
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- Errera_graph abstract "In the mathematical field of graph theory, the Errera graph is a graph with 17 vertices and 45 edges discovered by Alfred Errera. Published in 1921, it provides an example of how Kempe's proof of the four color theorem cannot work.Later, the Fritsch graph and Soifer graph provide two smaller counterexamples.The Errera graph is planar and has chromatic number 4, chromatic index 6, radius 3, diameter 4 and girth 3. All its vertices are of degree 5 or 6 and it is a 5-vertex-connected graph and a 5-edge-connected graph.".