Equation Icon  2∫ Cgrav[f;¯g] = κ-- dx √ ¯gf ℛ [¯g]αβγδf , k 2 αβ k γδ √ --∫ √ -- (4.13 ) Cgkh[C, ¯C;¯g] = 2 dx ¯gC¯αℛghk [¯g]C α,