Zig-Zag Numberlink is NP-Complete

When can t terminal pairs in an m × n grid be connected by t vertex-disjoint paths that cover all vertices of the grid? We prove that this problem is NP-complete. Our hardness result can be compared to two previous NP-hardness proofs: Lynch's 1975 proof without the "cover all vertices"...

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Main Authors: Adcock, Aaron (Author), Reidl, Felix (Author), Demaine, Erik D. (Contributor), Demaine, Martin L. (Contributor), O'Brien, Michael P. (Author), Villaamil, Fernando Sanchez (Author), Sullivan, Blair D. (Author)
Other Authors: Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science (Contributor)
Format: Article
Language:English
Published: Information Processing Society of Japan, 2015-11-23T17:47:19Z.
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Online Access:Get fulltext
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100 1 0 |a Adcock, Aaron  |e author 
100 1 0 |a Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science  |e contributor 
100 1 0 |a Demaine, Erik D.  |e contributor 
100 1 0 |a Demaine, Martin L.  |e contributor 
700 1 0 |a Reidl, Felix  |e author 
700 1 0 |a Demaine, Erik D.  |e author 
700 1 0 |a Demaine, Martin L.  |e author 
700 1 0 |a O'Brien, Michael P.  |e author 
700 1 0 |a Villaamil, Fernando Sanchez  |e author 
700 1 0 |a Sullivan, Blair D.  |e author 
245 0 0 |a Zig-Zag Numberlink is NP-Complete 
260 |b Information Processing Society of Japan,   |c 2015-11-23T17:47:19Z. 
856 |z Get fulltext  |u http://hdl.handle.net/1721.1/100008 
520 |a When can t terminal pairs in an m × n grid be connected by t vertex-disjoint paths that cover all vertices of the grid? We prove that this problem is NP-complete. Our hardness result can be compared to two previous NP-hardness proofs: Lynch's 1975 proof without the "cover all vertices" constraint, and Kotsuma and Takenaga's 2010 proof when the paths are restricted to have the fewest possible corners within their homotopy class. The latter restriction is a common form of the famous Nikoli puzzle Numberlink. Our problem is another common form of Numberlink, sometimes called Zig-Zag Numberlink and popularized by the smartphone app Flow Free. 
520 |a National Science Foundation (U.S.) (Grant CCF-1161626) 
520 |a United States. Defense Advanced Research Projects Agency (United States. Air Force Office of Scientific Research Grant FA9550-12-1-0423) 
546 |a en_US 
655 7 |a Article 
773 |t Journal of Information Processing