active f X mark if X c f true active if true X Y mark X active if false X Y mark Y mark f X active f mark X mark if X1 X2 X3 active if mark X1 mark X2 X3 mark c active c mark true active true mark false active false f mark X f X f active X f X if mark X1 X2 X3 if X1 X2 X3 if X1 mark X2 X3 if X1 X2 X3 if X1 X2 mark X3 if X1 X2 X3 if active X1 X2 X3 if X1 X2 X3 if X1 active X2 X3 if X1 X2 X3 if X1 X2 active X3 if X1 X2 X3 active 1 f 1 mark 1 if 3 c 0 true 0 false 0 INNERMOST ./TRS/TRCSR/inn/Ex5_Zan97_iGM.trs