  We present an efficient algorithm for computing the partial bisimulation
preorder and equivalence for labeled transitions systems. The partial
bisimulation preorder lies between simulation and bisimulation, as only a part
of the set of actions is bisimulated, whereas the rest of the actions are
simulated. Computing quotients for simulation equivalence is more expensive
than for bisimulation equivalence, as for simulation one has to account for the
so-called little brothers, which represent classes of states that can simulate
other classes. It is known that in the absence of little brother states,
(partial bi)simulation and bisimulation coincide, but still the complexity of
existing minimization algorithms for simulation and bisimulation does not
scale. Therefore, we developed a minimization algorithm and an accompanying
tool that scales with respect to the bisimulated action subset.
