equation icon  2@[a@b]f + 2x[ab]@f = 0, (43) 2@[a@b]vc + 2x[ab]@vc + harhbshctRrstdvd - 2x[a|c|xb]eve = 0, (44) c [@,@a] f + xa@f + xa @cf = 0, (45) [@,@a]vb + xa@vb + xac@cvb - xbxaeve + xabxeve + tchaehbfRcefdvd = 0. (46)