equation icon  ( ) guu = - (1 + raa_O_a)2 + r2 aa - wab_O_b (aa - wac_O_c) - r2S + O(r3), (171) ( ) g = - 1 + ra _O_b + 2r2S _O_ + r(a - w _O_b)+ 2r2S + O(r3), (172) ua b 3 a a ab 3 a ( 1 ) 1 1 gab = dab - 1 + -r2S _O_a_O_b - -r2Sab + -r2 (Sa_O_b + _O_aSb) + O(r3). (173) 3 3 3