The following dissertation is a collection of four stand-alone research papers. The focus of my research is on the interplay of immigration, native human-capital investment and the resulting consequences for the labour market outcome of natives and necessary implications for the immigration...

This paper investigates a dynamic general equilibrium model with search. In particular, search externalities are reßected by an increasing returns to scale matching function, which may imply an indeterminate equilibrium. Hence, the model is capable to generate business ßuctuations, driven by...