DISCRETE APPLIED MATHEMATICS VOLUME 89, Numbers 1-3, 1 December 1998 Contents Invited paper Foreword E. Balas Disjunctive programming: Properties of the convex hull of feasible points Contributions L Babe! Triangulating graphs with few P,'s A. Brandstadt, V.B. Le and T. Szymezak The complexity of some problems related to Graph 3-colorability H. Cameron Fringe thickness and maximum path length of binary trees K. Ciebiera and A. Malinowski Efficient broadcasting with linearly bounded faults J. Gomez, C. Padro and S. Perennes Large generalized cycles N. Guttmann-Beck and R. Hassin Approximation algorithms for min-sum p-clustering .G. Kirkpatrick, K.M adhukar Reddy, C. Pandu Rangan and . Srinivasan Partial and perfect path covers of cographs P. Sreenivasa Kumar and C.E. Veni Madhavan Minimal vertex separators of chordal graphs B. Lenze Linking discrete orthogonality with dilation and translation for incom plete sigma-pi neural networks of Hopfield-type H. Martini and A. Schdébel Median hyperplanes in normed spaces — a survey D. Pisinger A fast algorithm for strongly correlated knapsack problems W.F.J. Verhaegh, P.E.R. Lippens, E.H.L. Aarts, J.L. van Meerbergen and A. van der Werf The complexity of multidimensional periodic scheduling S.S. Yu d-minimal languages Note A. Hertz On perfect switching classes Communications J. Huang A note on spanning local tournaments in locally semicomplete digraphs M. Ouyang How good are branching rules in DPLL? Author Index