-- POPPUSHproof Derivation of pop(push(x,s)) ~ s Applying the axiom resp. theorem push(x,(f,i)) = (upd(suc(i),x,f),suc(i)) at position [0,0] of the preceding formula leads to Any f i:(pop((upd(suc(i),x,f),suc(i))) ~ (f,i) & s = (f,i)) Simplifying the preceding formula leads to Any f i:(pop(upd(suc(i),x,f),suc(i)) ~ (f,i) & s = (f,i)) Applying the axiom resp. theorem pop(f,i) = (f,pred(i)) at position [0,0,0] of the preceding formula leads to Any f i:((upd(suc(i),x,f),pred(suc(i))) ~ (f,i) & s = (f,i)) Applying the axiom resp. theorem pred(suc(i)) = i at position [0,0,0,1] of the preceding formula leads to Any f i:((upd(suc(i),x,f),i) ~ (f,i) & s = (f,i)) Applying the theorem (upd(i,x,f),j) ~ (f,j) <=== i > j at position [0,0] of the preceding formula leads to Any f i:(suc(i) > i & s = (f,i)) Applying the axiom resp. theorem suc(i) > i at position [0,0] of the preceding formula leads to Any f i:(True & s = (f,i)) Simplifying the preceding formula leads to Any f i:(s = (f,i)) Applying the theorem True ===> Any f i:(s = (f,i)) at position [] of the preceding formula leads to All s0:(Any f2 i4:(s0 = (f2,i4))) ==> Any f i:(s = (f,i)) Simplifying the preceding formula leads to True Number of proof steps: 9 Solutions: True