“…QUBE++ is able to solve 10% of the instances that defied all the participants in the QBF evaluation, and it is up to one, two, and nearly three orders of magnitude faster than, respectively, QUBEREL, QUBEBJ and SEMPROP, i.e., the best QBF solvers on nonrandom instances according to [8]. We have also tried QUBE++ on a test set of challenging real-world SAT benchmarks together with QUBEREL, the previous best version of QUBE, and ZCHAFF, the winner of SAT 2002 competition [1] and one of the best solvers in SAT 2003 competition [2] on real-world SAT instances. The results show that QUBE++ is able to conquer about 90% of the test set, and it loses, medianly, only a factor of two from ZCHAFF, while QUBEREL, conquers only 50% of the test set and it is, medianly, one order of magnitude slower than ZCHAFF.…”