The Complexity of Planar Boolean CSP with Complex Weights

Heng Guo, Tyson Williams

Research output: Chapter in Book/Report/Conference proceedingConference contribution


We prove a complexity dichotomy theorem for symmetric complex-weighted Boolean #CSP when the constraint graph of the input must be planar. The problems that are #P-hard over general graphs but tractable over planar graphs are precisely those with a holographic reduction to matchgates. This generalizes a theorem of Cai, Lu, and Xia for the case of real weights. We also obtain a dichotomy theorem for a symmetric arity 4 signature with complex weights in the planar Holant framework, which we use in the proof of our #CSP dichotomy. In particular, we reduce the problem of evaluating the Tutte polynomial at the point (3; 3) to counting the number of Eulerian orientations over planar 4-regular graphs to show the latter is #P-hard. This strengthens a theorem by Huang and Lu to the planar setting. Our proof techniques combine
new ideas with refinements and extensions of existing techniques. These include planar pairings, the recursive unary construction, the anti-gadget technique, and pinning in the Hadamard basis.
Original languageEnglish
Title of host publicationAutomata, Languages, and Programming - 40th International Colloquium, ICALP 2013, Riga, Latvia, July 8-12, 2013, Proceedings, Part I
Number of pages12
ISBN (Electronic)978-3-642-39205-4
Publication statusAccepted/In press - 12 Apr 2013
EventICALP 2013 - Riga, Latvia
Duration: 8 Jul 201312 Jul 2013


ConferenceICALP 2013
Internet address


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