Φ Φ 01 := 1 2 R a b l a m b , Φ Φ 10 := 1 2 R a b l a m ¯ ¯ b = Φ Φ 01 ¯ ¯ , Φ Φ 02 := 1 2 R a b m a m b , Φ Φ 20 := 1 2 R a b m ¯ ¯ a m ¯ ¯ b = Φ Φ 02 ¯ ¯ , Φ Φ 12 := 1 2 R a b m a n b , Φ Φ 21 := 1 2 R a b m ¯ ¯ a n b = Φ Φ 12 ¯ ¯ .