User grzegorz jaśkiewicz - MathOverflowmost recent 30 from http://mathoverflow.net2013-05-25T10:04:50Zhttp://mathoverflow.net/feeds/user/17827http://www.creativecommons.org/licenses/by-nc/2.5/rdfhttp://mathoverflow.net/questions/75501/hamiltonian-paths-in-subgraphs-of-rectangular-lattice-graphsHamiltonian paths in subgraphs of rectangular lattice graphsGrzegorz Jaśkiewicz2011-09-15T10:52:57Z2011-09-15T14:20:47Z
<p>Is following decision problem NP-hard / NP-complete:</p>
<ol>
<li>Having vertex-induced subgraph of rectangular lattice graph determine if any Hamiltonian path exists</li>
<li>Having vertex-induced subgraph of rectangular lattice graph determine if exists Hamiltonian path starting at given point (path end can be anywhere)</li>
</ol>
<p>Please give me some references.</p>
http://mathoverflow.net/questions/75501/hamiltonian-paths-in-subgraphs-of-rectangular-lattice-graphsComment by Grzegorz JaśkiewiczGrzegorz Jaśkiewicz2011-09-15T20:59:57Z2011-09-15T20:59:57ZI have some funny idea:
1. Draw cubic planar graph on white piece of paper with black pen, so that there are no edge intersections.
2. Take a photo with digital camera.
Now all pixels in photo form square lattice, black pixels are verteices of lattice subgraph. With correct lens scaling this would produce good embedding ;)http://mathoverflow.net/questions/75501/hamiltonian-paths-in-subgraphs-of-rectangular-lattice-graphsComment by Grzegorz JaśkiewiczGrzegorz Jaśkiewicz2011-09-15T12:41:50Z2011-09-15T12:41:50Z1. NP-complete, answer is here: <a href="http://research.cs.queensu.ca/home/daver/Pubs/MyPDF/superThin.pdf" rel="nofollow">research.cs.queensu.ca/home/daver/Pubs/MyPDF/…</a>
2. NP-complete by polyminal reduction to problem 1 - just check Hamiltonian path for every vertexhttp://mathoverflow.net/questions/75501/hamiltonian-paths-in-subgraphs-of-rectangular-lattice-graphsComment by Grzegorz JaśkiewiczGrzegorz Jaśkiewicz2011-09-15T12:24:26Z2011-09-15T12:24:26ZIs it obvious that cublic planar graph is a vertex-induced subgraph of rectangular lattice graph?