  Mathematicians had little idea whether the easy-to-state union-closed
conjecture was true or false even after $40$ years. However, last winter saw a
surge of interest in the conjecture and its variants, initiated by the
contribution of a researcher at Google. Justin Gilmer [arXiv:2211.09055] made a
significant breakthrough by discovering a first constant lower bound for the
proportion of the most common element in a union-closed family.
