  This note is devoted to a discussion of the potential links and differences
between three topics: regularization by noise, convex integration, spontaneous
stochasticity. All of them deal with the effect on large scales of a
small-scale perturbation of fluid dynamic equations. The effects sometimes have
something in common, like convex integration and spontaneous stochasticity,
sometimes they look the opposite, as in regularization by noise. We are not
aware of rigorous links or precise explanations of the differences, and hope to
drive new research with this comparative examination.
