From charge transfer type insulator to superconductor

We propose a microscopic model Hamiltonian to account for impurity doping induced insulator-superconductor transition and the coexistence of antiferromagnetism and superconductivity in the high-Tc cuprates. The crossover from non Fermi liquid to Fermi liquid regime characterized by delocalization of delocalization of d electrons at Cu sites is discussed

A new proof of a theorem of Mansour and Sun

We give a new proof of a theorem of Mansour and Sun by using number theory and Rothe's identity.Comment: 3 pages, to appear in European J. Combin., see also http://math.univ-lyon1.fr/~gu