  An incomparable feature of the chiral quark soliton model as compared with
many other effective models like the MIT bag model is that it can give
reasonable predictions not only for quark distributions but also for antiquark
distributions. This will be exemplified by the argument on the positivity
constraint for $\bar{u} (x) + \bar{d} (x)$ as well as the Soffer inequality for
quark and antiquark distributions. We also explain how the model can resolve
the so-called nucleon spin puzzle without assuming large gluon polarization at
the low energy scale.
