“Art is what makes life more interesting than art”—this is the title the artist Robert Filliou gave to one of his “multiples,” a work consisting of many variations upon a theme. Filliou, who certainly pushed art beyond its formal limits, used plays, action poems, street performances, happenings, objects, and other mixed media to create undefinable pieces. Presenting a selection of his famous multiples, “Dear Skywalker” also includes Filliou’s collaborations with fellow nonconformists George Brecht, Emmett Williams, and Daniel Spoerri. —E.C.