Sensitivity of internal structure to the surface boundary condition

Proper surface boundary conditions for interior models of late-type stars require a detailed understanding of the structure of the stellar atmosphere. Much progress still remains to be made on several problems which are separated here for convenience but which are obviously closely interrelated: 1) the problems of the treatment of convection and of the uncertainties in convective efficiency and the related problem of convective overshoot; 2) the problem of the opacities and of the molecular equilibrium in late-type stellar atmospheres; 3) the problem of the radiative transfer itself and its implications for the construction of atmospheric models of great spectral complexity. (Auth.)