To classify Gabriel Lester’s “Unresolved Extravaganza” (also known as “Unhappen,” “Apple Z,” “Præmonitions,” “The Nine Day Week,” and “Seven Hills Secrets”) as a solo show would not be correct, but it is exactly this fallacy that reveals his distinctive métier. For this overview of Lester’s collaborative works of the past twenty years, the artist steadfastly continues to do what he’s always done—namely, work with others. The exhibition was curated and produced by the artist himself—Lester had been invited to do the show by de Appel’s director, Lorenzo Benedetti, but when Benedetti was