Symbols of America are the theme of Robert Logo’s simultaneous Chelsea exhibitions. More subtle than the American flag sculpture and monumental drawing of the U.S. Capitol at Petzel are the graphite facsimiles of Abstract Expressionist paintings on view at Metro Pictures. There’s a lot of fun to be had marveling at Longo’s virtuosic replication of painterly textures found in masterpieces by Still, Pollock, Mitchell and Newman, and even more grist for thought regarding the nature of handcrafted art objects. Though Longo’s air of cool detachment might seem a world away from the hot-blooded painters he engages here, “Gang of Cosmos,” as the exhibition is called, also feels personal in a way. After all, an aspiring artist from Long Island might have explored art history just like this, through reproductions rather than exalted encounters with the real things.