Nine paintings by two canonical artists face off at the Vito Schnabel gallery (appointments required). The ambience of the aseptic space, with its gleaming white floor, has a rather diminishing effect on the modestly sized modernist works, which were made between the nineteen-twenties and the mid-fifties. But if the show is more a curt essay than a conspiratorial tête-à-tête, that’s not really a problem—the mood suits the teasing, post-Dadaist rigor of the works on view.