pwbo is a parallel Boolean optimization solver. For the MaxSAT'12 evaluation pwbo is run with two threads.
An unsatisfiability-based algorithm is used to search on the lower bound of the optimal solution, while at the
same time a linear search is performed on the upper bound of the optimal solution.

pwbo2.0 uses the unsatisfiability-based algorithm of wbo1.6 and on the upper bound search uses a dynamic
heuristic that determines which encoding (sorters, totalizer or pseudo-Boolean representation) should be 
used to represent the objective function.

References:
R. Martins, V. Manquinho, I. Lynce, Clause Sharing in Parallel MaxSAT, LION 2012.
R. Martins, V. Manquinho, I. Lynce, Exploiting Cardinality Encodings in Parallel Maximum Satisfiability, ICTAI 2011.
R. Martins, V. Manquinho, I. Lynce, Parallel Search for Boolean Optimization, RCRA 2011.