let a be Int_position; :: thesis: for i being Integer
for n being Nat
for I being Program of SCMPDS holds for-down (a,i,n,I) = ((a,i) <=0_goto ((card I) + 3)) ';' ((I ';' (AddTo (a,i,(- n)))) ';' (goto (- ((card I) + 2))))

let i be Integer; :: thesis: for n being Nat
for I being Program of SCMPDS holds for-down (a,i,n,I) = ((a,i) <=0_goto ((card I) + 3)) ';' ((I ';' (AddTo (a,i,(- n)))) ';' (goto (- ((card I) + 2))))

let n be Nat; :: thesis: for I being Program of SCMPDS holds for-down (a,i,n,I) = ((a,i) <=0_goto ((card I) + 3)) ';' ((I ';' (AddTo (a,i,(- n)))) ';' (goto (- ((card I) + 2))))
let I be Program of SCMPDS; :: thesis: for-down (a,i,n,I) = ((a,i) <=0_goto ((card I) + 3)) ';' ((I ';' (AddTo (a,i,(- n)))) ';' (goto (- ((card I) + 2))))
set i1 = (a,i) <=0_goto ((card I) + 3);
set i2 = AddTo (a,i,(- n));
set i3 = goto (- ((card I) + 2));
thus for-down (a,i,n,I) = ((((a,i) <=0_goto ((card I) + 3)) ';' I) ';' (AddTo (a,i,(- n)))) ';' (goto (- ((card I) + 2))) by SCMPDS_7:def 2
.= ((a,i) <=0_goto ((card I) + 3)) ';' ((I ';' (AddTo (a,i,(- n)))) ';' (goto (- ((card I) + 2)))) by SCMPDS_7:2 ; :: thesis: verum