let s be State of ; :: thesis: for I being Program of
for a being Int_position
for k1 being Integer st s . (DataLoc (s . a),k1) <> 0 holds
( if=0 a,k1,I is_closed_on s & if=0 a,k1,I is_halting_on s )
let I be Program of ; :: thesis: for a being Int_position
for k1 being Integer st s . (DataLoc (s . a),k1) <> 0 holds
( if=0 a,k1,I is_closed_on s & if=0 a,k1,I is_halting_on s )
let a be Int_position ; :: thesis: for k1 being Integer st s . (DataLoc (s . a),k1) <> 0 holds
( if=0 a,k1,I is_closed_on s & if=0 a,k1,I is_halting_on s )
let k1 be Integer; :: thesis: ( s . (DataLoc (s . a),k1) <> 0 implies ( if=0 a,k1,I is_closed_on s & if=0 a,k1,I is_halting_on s ) )
set b = DataLoc (s . a),k1;
assume A1: s . (DataLoc (s . a),k1) <> 0 ; :: thesis: ( if=0 a,k1,I is_closed_on s & if=0 a,k1,I is_halting_on s )
set i = a,k1 <>0_goto ((card I) + 1);
set IF = if=0 a,k1,I;
set pIF = stop (if=0 a,k1,I);
set IsIF = Initialized (stop (if=0 a,k1,I));
set s3 = s +* (Initialized (stop (if=0 a,k1,I)));
set s4 = Computation (s +* (Initialized (stop (if=0 a,k1,I)))),1;
A2: IC (s +* (Initialized (stop (if=0 a,k1,I)))) = inspos 0 by FUNCT_4:26, SCMPDS_5:18;
A3: not DataLoc (s . a),k1 in dom (Initialized (stop (if=0 a,k1,I))) by SCMPDS_4:31;
not a in dom (Initialized (stop (if=0 a,k1,I))) by SCMPDS_4:31;
then A4: (s +* (Initialized (stop (if=0 a,k1,I)))) . (DataLoc ((s +* (Initialized (stop (if=0 a,k1,I)))) . a),k1) = (s +* (Initialized (stop (if=0 a,k1,I)))) . (DataLoc (s . a),k1) by FUNCT_4:12
.= s . (DataLoc (s . a),k1) by A3, FUNCT_4:12 ;
Computation (s +* (Initialized (stop (if=0 a,k1,I)))),(0 + 1) = Following (Computation (s +* (Initialized (stop (if=0 a,k1,I)))),0 ) by AMI_1:14
.= Following (s +* (Initialized (stop (if=0 a,k1,I)))) by AMI_1:13
.= Exec (a,k1 <>0_goto ((card I) + 1)),(s +* (Initialized (stop (if=0 a,k1,I)))) by Th22 ;
then A5: IC (Computation (s +* (Initialized (stop (if=0 a,k1,I)))),1) = ICplusConst (s +* (Initialized (stop (if=0 a,k1,I)))),((card I) + 1) by A1, A4, SCMPDS_2:67
.= inspos (0 + ((card I) + 1)) by A2, Th23 ;
A6: card (if=0 a,k1,I) = (card I) + 1 by Th15;
then A7: inspos ((card I) + 1) in dom (stop (if=0 a,k1,I)) by Th25;
Initialized (stop (if=0 a,k1,I)) c= s +* (Initialized (stop (if=0 a,k1,I))) by FUNCT_4:26;
then stop (if=0 a,k1,I) c= Computation (s +* (Initialized (stop (if=0 a,k1,I)))),1 by AMI_1:81, SCMPDS_4:57;
then (Computation (s +* (Initialized (stop (if=0 a,k1,I)))),1) . (inspos ((card I) + 1)) = (stop (if=0 a,k1,I)) . (inspos ((card I) + 1)) by A7, GRFUNC_1:8
.= halt SCMPDS by A6, Th25 ;
then A8: CurInstr (Computation (s +* (Initialized (stop (if=0 a,k1,I)))),1) = halt SCMPDS by A5;

now

let k be Element of NAT ; :: thesis: IC (Computation (s +* (Initialized (stop (if=0 a,k1,I)))),b₁) in dom (stop (if=0 a,k1,I))

per cases ( 0 < k or k = 0 ) ;

suppose 0 < k ; :: thesis: IC (Computation (s +* (Initialized (stop (if=0 a,k1,I)))),b₁) in dom (stop (if=0 a,k1,I))

then 1 + 0 <= k by INT_1:20;
hence IC (Computation (s +* (Initialized (stop (if=0 a,k1,I)))),k) in dom (stop (if=0 a,k1,I)) by A7, A5, A8, AMI_1:52; :: thesis: verum

end;

suppose k = 0 ; :: thesis: IC (Computation (s +* (Initialized (stop (if=0 a,k1,I)))),b₁) in dom (stop (if=0 a,k1,I))

then Computation (s +* (Initialized (stop (if=0 a,k1,I)))),k = s +* (Initialized (stop (if=0 a,k1,I))) by AMI_1:13;
hence IC (Computation (s +* (Initialized (stop (if=0 a,k1,I)))),k) in dom (stop (if=0 a,k1,I)) by A2, SCMPDS_4:75; :: thesis: verum

end;

end;

end;

hence if=0 a,k1,I is_closed_on s by Def2; :: thesis: if=0 a,k1,I is_halting_on s
ProgramPart (s +* (Initialized (stop (if=0 a,k1,I)))) halts_on s +* (Initialized (stop (if=0 a,k1,I))) by A8, AMI_1:146;
hence if=0 a,k1,I is_halting_on s by Def3; :: thesis: verum