Rival

Another hypothesis for the same gap; every pair of rivals is bound to one observable that would come out differently under each.

The competition matrix of a gap lists, for each pair of hypotheses, the one measurable outcome where they predict differently. A hypothesis that predicts what its rivals predict has nothing to contest and earns no experiment. On the page a rival arrives from the engine named only by a machine label; the card prints a plain axis name with one line of gloss and keeps the raw label folded underneath.