ƚ [ a .  & & MathType-@F Times New Roman؟ww w f-2 2yTimes New Roman؟ww w f-2 n3y2 1y2 n 1yTimes New Roman؟ww w f-2 Tty2 NtySymbolk P؟ww w f-2 `+y2 -y & "System f !-