In the empirical analysis of financial time series, multivariate GARCH models have been used in various forms. In most cases it is not well understood how the use of a restricted model has to be paid with loss of valuable information. We investigate the structural implications of two alternative...

A separation heuristic for mixed integer programs is presented that theoretically allows one to derive several families of " strong" valid inequalities for specific models and compuationally gives results as good as or better than those obtained from several existing separation routines...

This paper is concerned with the determinants of international steam-coal trade. Most work in projecting coal trade has been either qualitative (a consensus of experts) or, if quantitative, has been based on competitive spatial-equilibrium models. Unfortunately, the competitive model of trade...