According to the artist's explanation in a note-card study for the work: "The first term of the language fraction refers to the tangential relationship of the film—color in this case—and the border. The second term refers to its position (the film) as regards the sense of enclosure (enclosure considered as condition of position)." Using Bochner's explanation, one can therefore see that in the far left square of the work the boundary of the color surface is at the border and in the enclosure; in the second square the boundary of the color surface is over the border and in the enclosure; in the third square the boundary of the color surface has no relationship to the border (this is why the first term of the fraction is empty) and is in the enclosure; and in the last square the boundary is at the border but out of the enclosure. Theory of Boundaries is in this way both a statement about the underlying formal principles of painting, and painting itself.
On view in the National Gallery's East Building, Concourse Gallery 29F.