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A planar graph cannot contain K 3,3 as a minor; an outerplanar graph cannot contain K 3,2 as a minor (These are not sufficient conditions for planarity and outerplanarity, but necessary). Conversely, every nonplanar graph contains either K 3,3 or the complete graph K 5 as a minor; this is Wagner's theorem. [9] Every complete bipartite graph.
Kuratowski's theorem states that a finite graph is planar if it is not possible to subdivide the edges of or ,, and then possibly add additional edges and vertices, to form a graph isomorphic to . Equivalently, a finite graph is planar if and only if it does not contain a subgraph that is homeomorphic to K 5 {\displaystyle K_{5}} or K 3 , 3 ...
Proof without words that a hypercube graph is non-planar using Kuratowski's or Wagner's theorems and finding either K 5 (top) or K 3,3 (bottom) subgraphs. Wagner published both theorems in 1937, [1] subsequent to the 1930 publication of Kuratowski's theorem, [2] according to which a graph is planar if and only if it does not contain as a subgraph a subdivision of one of the same two forbidden ...
A finite graph is planar if and only if it does not contain a subgraph that is a subdivision of the complete graph K 5 or the complete bipartite graph K 3,3 (utility graph). A subdivision of a graph results from inserting vertices into edges (for example, changing an edge • —— • to • — • — • ) zero or more times.
However, every planar drawing of a complete graph with five or more vertices must contain a crossing, and the nonplanar complete graph K 5 plays a key role in the characterizations of planar graphs: by Kuratowski's theorem, a graph is planar if and only if it contains neither K 5 nor the complete bipartite graph K 3,3 as a subdivision, and by ...
In other words, the graph , is not planar. Kazimierz Kuratowski stated in 1930 that K 3 , 3 {\displaystyle K_{3,3}} is nonplanar, [ 15 ] from which it follows that the problem has no solution. Kullman (1979) , however, states that "Interestingly enough, Kuratowski did not publish a detailed proof that [ K 3 , 3 {\displaystyle K_{3,3}} ] is non ...
In graph theory, an undirected graph H is called a minor of the graph G if H can be formed from G by deleting edges, vertices and by contracting edges.. The theory of graph minors began with Wagner's theorem that a graph is planar if and only if its minors include neither the complete graph K 5 nor the complete bipartite graph K 3,3. [1]
a finite graph is planar if and only if it contains no subgraph homeomorphic to K 5 (complete graph on five vertices) or K 3,3 (complete bipartite graph on six vertices, three of which connect to each of the other three). In fact, a graph homeomorphic to K 5 or K 3,3 is called a Kuratowski subgraph.