LPAR-21: Editor's Preface

This volume contains the papers presented at LPAR-21: the 21st International Conference on Logic for Programming, Artificial Intelligence and
Reasoning (LPAR-21), held 8th-12th May 2017, at Cresta Riley's Hotel in Maun, Botswana.

Following the call for papers, LPAR-21 received 68 abstracts, materializing into 54 submissions. Each submission was reviewed by a panel of 48 Program Committee (PC) members. The PC was assisted by 47 additional reviewers and decided to accept 30 papers.  In addition to the presentation of these regular papers, LPAR-21 included the following invited talks:

• Rupak Majumdar (Max Planck Institute for Software Systems, Germany):
  Programming by Composing Filters
• Stephen Muggleton (Imperial College London, United Kingdom):
  Meta-Interpretive Learning of Logic Programs
• Willem Visser (Stellenbosch University, South Africa):
  Probabilistic Symbolic Execution: A New Hammer

as well as seven short talks presenting further papers.

The EasyChair system provided an indispensible platform for all matters related to the reviewing process, production of these proceedings, program and web page generation, and registration of participants.

Collocated with LPAR-21 was the 12th International Workshop on the Implementation of Logics (IWIL), organized by Stephan Schulz, Geoff Sutcliffe, and Josef Urban.

The local conference organisation was done by Geoff Sutcliffe.