2013

Inapproximability for Antiferromagnetic Spin Systems in the Tree Non-Uniqueness Region

Galanis, Andreas, Stefankovic, Daniel, Vigoda, Eric

Understand

A remarkable connection has been established for antiferromagnetic 2-spin systems, including the Ising and hard-core models, showing that the computational complexity of approximating the partition function for graphs with maximum degree D undergoes a phase transition that coincides with the statistical physics uniqueness/non-uniqueness phase transition on the infinite D-regular tree.

  • Despite this clear picture for 2-spin systems, there is little known for multi-spin systems.
  • We present the first analog of the above inapproximability results for multi-spin systems.
  • The main difficulty in previous inapproximability results was analyzing the behavior of the model on random D-regular bipartite graphs, which served as the gadget in the reduction.

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