prolog: https://en.wikibooks.org/wiki/Prolog/Introduction

inductive logic programming: https://en.wikipedia.org/wiki/Inductive_logic_programming

horn clause: https://en.wikipedia.org/wiki/Horn_clause

inductive logic programming: http://www.doc.ic.ac.uk/~shm/ilp.html http://www.doc.ic.ac.uk/~shm/ilp_theory.html