  In this note we disprove a conjecture of Kuzmin and Warmuth claiming that
every family whose VC-dimension is at most d admits an unlabeled compression
scheme to a sample of size at most d. We also study the unlabeled compression
schemes of the joins of some families and conjecture that these give a larger
gap between the VC-dimension and the size of the smallest unlabeled compression
scheme for them.
