The means of distribution — also known as the market — is a looming subject in the art world these days, and Allan McCollum and Stephen Prina have clearly been giving it some thought. So perhaps has Friedrich Petzel, who scheduled their side-by-side solo shows in his gallery and its generous project space next door.

Mr. McCollum has long questioned notions of originality and uniqueness with found motifs (in both two and three dimensions) and intimations of mass production, all the while sticking largely to abstraction. For "The Shapes Project," he devised a system that can, in theory, eventually generate enough unique motifs that everyone in the world can have one. Eventually is the key word here. In the meantime, Mr. McCollum has used a computer graphics program to produce 7,056 examples of the shapes, small and framed, in black on white. They resemble emblems, irregular hand grenades or exotic knife blades and are displayed wall-to-wall on a ramp with 98 1-1/4-inch shelves that fills most of the gallery. The effect, of a stadium full of art looking at you, the viewer, is quite amazing.

Next door, Mr. Prina's "Second Sentence of Everything I Read Is You" orchestrates his interests in painting, music and appropriation into a quietly delirious multimedia experience. The work is a pink-carpeted listening lounge with four big plywood ottomans whose pink cushions qualify as paintings. But — as a spotlighted speaker hints — the main event is a choral piece written and recorded by Mr. Prina. The music is hauntingly tender, despite that fact that its lyrics quote art critics and economists.

This weirdly romantic environment is a world unto itself in more ways than one. It all fits into the bases of the ottomans, which double as shipping crates. Mr. Prina intends that the piece will travel to interested museums and galleries without benefit of cleaning or conservation until it literally falls apart, and is just a memory.      ROBERTA SMITH