Two years ago, in his last solo exhibition, Franz Graf showed work in only three rooms of this gallery; each room contained one work, hung at the precise center of the wall. Now, in the same gallery, at exactly the same places, Graf has exhibited three new works with exactly the same theme: variations on the circle. Yet the difference in the two artistic conceptions of this theme could hardly be greater. The pieces shown in 1986 were canvases worked in black india ink. The strongly centralized images radiated in jagged or wavy lines; in some cases, the dark/light contrast between the lines and