[lorvoqjf] Thematic move

Create a computer program to find "thematic" moves in chess, a vaguely defined term seen in chess problems, opening theory, and possibly others.  There are many examples of the label, so perhaps this is a good task for machine learning.

Thematic might mean, leading to an important idea, a mechanism, a theme, seen in many variations (including variations not starting with this thematic move).  It is not necessarily the strongest move.  There is often a strong element of pedagogy in thematic moves.

Discovering and extracting the commonalities between different but related things is an important task in many fields.