Description of optiriss, submitted by Norbert Manthey to the MAXSAT Evaluation optiriss is an extension of the MaxSAT Solver Open-WBO (see details below) As a SAT solver, Riss 5.0.2 is used. Furthermore, the solver has been enabled to support incomplete solving, by printing an interpretation for each optimization bound that has been found by the algorithm. The solver also allows to simplify the problem before solving it. Yet, the printed model is not (always) correct. However, the reported bounds are correct if simplification is used. The simplification can also be applied to formulas that have only soft unit clauses, and no soft clauses of greater length, as simplification would turn the formulas into this shape. Running optiriss (best known configuration): ./optiriss -solverConfig=INCSOLVE