Description: Define the covers relation (on the Hilbert lattice). Definition 3.2.18 of PtakPulmannova p. 68, whose notation we use. Ptak/Pulmannova's notation A is read " B covers A " or " A is covered by B " , and it means that B is larger than A and there is nothing in between. See cvbr and cvbr2 for membership relations. (Contributed by NM, 4-Jun-2004) (New usage is discouraged.)