I have worked on various subjects, but ever since my years as PostDoc, I have
been fascinated by Datalog, a logical programming language for reasoning and
database querying. I will start this talk with a short introduction to Datalog,
followed by an overview of some theoretical results on Datalog variants. This
will be interleaved with a tale of four Datalog-related companies I co-founded:
DLVSystem, Lixto, Wrapidity, and DeepReason.ai. I will also comment on the
difficulties an academic has to face when spinning out a start-up, and on the
satisfaction you may experience when your results are used in practice.