Discrete Mathematics Volume 210, Numbers 1-3, 6 January 2000 Contents Preface P. Leroux and D. Stanton Contributions S.A. Abramov, M. PetkovsSek and A. Ryabenko Special formal series solutions of linear operator equations E.M. Feichtner and D.N. Kozlov On subspace arrangements of type 7 27 S. Fereti¢c An alternative method for q-counting directed column-convex polyominoes 55 O. Guibert Stack words, standard Young tableaux, permutations with forbidden subsequences and planar maps 71 Hoang Ngoc Minh and G. Jacob Symbolic integration of meromorphic differential systems via Dirichlet functions 87 W.P. Johnson Some polynomials associated with up-down permutations 117 G. Melangon Lyndon factorization of sturmian words 137 M. Schlosser Summation theorems for multidimensional basic hypergeometric series by determinant evaluations 151 B. Sturmfels Solving algebraic equations in terms of ./-hypergeometric series 171 Author index to volume 210 183 Ss