Invited Articles Foreword

The Invited Articles section of this issue consists of three papers. The first is “Shellability is NPcomplete,” by Xavier Goaoc, Pavel Paták, Zuzana Patáková, Martin Tancer, and Uli Wagner, which won the best-paper award at the 34th International Symposium on Computational Geometry (SoCG’17). We want to thank the SoGS Program Committee for their help in selecting this invited paper and editor Jean-Daniel Boissonnat for handling the paper. Next is “Towards Verifying Nonlinear Integer Arithmetic,” by Paul Beame and Vincent Liew, invited from the 39th International Conference on Computer Aided Verification (CAV’17). We want to thank the CAV Program Committee for their help in selecting this invited paper and editor Rajeev Alur for handling the paper. Last, but not least, is the paper “On the Computability of Conditional Probability,” by Nathanael L. Ackerman, Cameron E. Freer, and Daniel M. Roy, invited from the 26th Annual IEEE Symposium on Logic in Computer Science (LICS’11). We want to thank the LICS Program Committee for their help in selecting this invited paper and editor Nachum Dershowitz for handling the paper.