a__fact X a__if a__zero mark X s 0 prod X fact p X a__add 0 X mark X a__add s X Y s a__add mark X mark Y a__prod 0 X 0 a__prod s X Y a__add mark Y a__prod mark X mark Y a__if true X Y mark X a__if false X Y mark Y a__zero 0 true a__zero s X false a__p s X mark X mark fact X a__fact mark X mark if X1 X2 X3 a__if mark X1 X2 X3 mark zero X a__zero mark X mark prod X1 X2 a__prod mark X1 mark X2 mark p X a__p mark X mark add X1 X2 a__add mark X1 mark X2 mark s X s mark X mark 0 0 mark true true mark false false a__fact X fact X a__if X1 X2 X3 if X1 X2 X3 a__zero X zero X a__prod X1 X2 prod X1 X2 a__p X p X a__add X1 X2 add X1 X2 a__fact 1 a__if 3 a__zero 1 mark 1 s 1 0 0 prod 2 fact 1 p 1 a__add 2 a__prod 2 true 0 false 0 a__p 1 if 3 zero 1 add 2 INNERMOST ./TRS/TRCSR/inn/ExIntrod_Zan97_GM.trs