Equation Icon  bulk a2 = AE (4∫) + BI (4), 1-- αβμν μν 2 E(4) = 64 E(R αβμνR − 4R μνR + R ), 1 ∫ αβμν μν 1 2 I(4) = − --- (RαβμνR − 2R μνR + --R ) . (274 ) 64 E 3