Is the NUTS algorithm correct?

Abstract

This paper is devoted to investigate whether the popular No U-turn (NUTS) sampling algorithm is correct, i.e.\ whether the target probability distribution is \emph{exactly} conserved by the algorithm. It turns out that one of the Gibbs substeps used in the algorithm cannot always be guaranteed to be correct.

Some statements in the paper are misleading. It is possible to think of NUTS at not being a slice/Gibbs sampler and, with an alternative interpretation, it may be be possible to prove that the algorithm is correct. In addition the experiment reported in Figure 2 should have had many initial states drawn from the target rather than using a single value