WEAKLY SCREENED COULOMB INTERACTION AND PROPERTIES OF HTSCS

In order to explain the anisotropy of the energy gap observed in direc t photoemission experiments on the basis of the ''extended saddle-poin t singularities'' in the electron-energy spectrum lying close to the F ermi level, the assumption is made that the Coulomb interactions are w eakly screened, i.e. the Debye screening radius is much larger than th e lattice period; this makes the electron interaction anisotropic. Ano ther consequence of this assumption is that at low temperatures the no rmal-state resistivity is mostly defined by electron-electron scatteri ng. and its temperature dependence is rho is-proportional-to T. Some a spects of the model are discussed.