Big-Bang nucleosynthyesis: constraints on nuclear reaction rates, neutrino degeneracy, inhomogeneous and Brans-Dicke models

We review the recent progress in the Big-Bang nucleosynthesis which includes the standard and non-standard theory of cosmology, effects of neutrino degeneracy, and inhomogeneous nucleosynthesis within the framework of a Friedmann model. As for a non-standard theory of gravitation, we adopt a Brans-Dicke theory which incorporate a cosmological constant. We constrain various parameters associated with each subject.