Introduction to the Collection of Papers Celebrating the 20th Anniversary of TPLP

The first issue of the journal Theory and Practice of Logic Programming, or TPLP, was published in January 2001. This issue, the last one in the present volume, and the following issue, the first one in the next volume, comprise a collection of papers com-memorating and celebrating the twentieth anniversary of the journal. This celebratory collection comes with about one year delay due to the COVID-19 pandemic (but also, if we were to be entirely honest, because of a common human tendency to put things off). Whatever the true reason for the delay, the collection is finally here. We hope and expect it will prove to be a demonstration of the vitality of logic programming, and of a broad range of research directions it spawned in the past and continues to generate today. Logic programming computer a of research on automated theorem proving in logic the of the programming The these original of inspiration of