Pre-proceedings of the 27th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2017)

This volume constitutes the pre-proceedings of the 27th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2016), held on 10-12th October 2017 in Namur, Belgium, and co-located with the 19th International Symposium on Principles and Practice of Declarative Programming (PPDP 2017). After discussion at the symposium papers will go through a second round of refereeing and selection for the formal proceedings.