Machine learning and the Continuum Hypothesis

In January 2019 the journal Nature reported on an exciting development in Machine Learning: the very first issue of the journal Nature Machine Intelligence contains a paper that describes a learning problem whose solvability is neither provable nor refutable on the basis of the standard ZFC axioms of Set Theory. In this note K. P. Hart describes what the fuss is all about and indicates that maybe the problem is not so undecidable after all.