let N be non empty with_non-empty_elements set ; :: thesis: for S being non empty stored-program IC-Ins-separated definite realistic standard AMI-Struct of N
for il being Element of NAT
for i being Instruction of S st i is sequential holds
NIC (i,il) = {(succ il)}

let S be non empty stored-program IC-Ins-separated definite realistic standard AMI-Struct of N; :: thesis: for il being Element of NAT
for i being Instruction of S st i is sequential holds
NIC (i,il) = {(succ il)}

let il be Element of NAT ; :: thesis: for i being Instruction of S st i is sequential holds
NIC (i,il) = {(succ il)}

let i be Instruction of S; :: thesis: ( i is sequential implies NIC (i,il) = {(succ il)} )
assume A1: for s being State of S holds (Exec (i,s)) . (IC S) = succ (IC s) ; :: according to AMISTD_1:def 16 :: thesis: NIC (i,il) = {(succ il)}
now
let x be set ; :: thesis: ( x in {(succ il)} iff x in { (IC (Exec (i,ss))) where ss is Element of product the Object-Kind of S : IC ss = il } )
A2: now
reconsider il1 = il as Element of ObjectKind (IC S) by COMPOS_1:def 6;
reconsider I = i as Element of the Object-Kind of S . il by COMPOS_1:def 8;
consider t being State of S;
assume A3: x = succ il ; :: thesis: x in { (IC (Exec (i,ss))) where ss is Element of product the Object-Kind of S : IC ss = il }
reconsider f = ((IC S),il) --> (il1,I) as PartState of S by COMPOS_1:37;
reconsider u = t +* f as Element of product the Object-Kind of S by PBOOLE:155;
A4: dom (((IC S),il) --> (il1,I)) = {(IC S),il} by FUNCT_4:65;
then X: il in dom (((IC S),il) --> (il1,I)) by TARSKI:def 2;
A5: (ProgramPart u) /. il = u . il by COMPOS_1:38
.= (((IC S),il) --> (il1,I)) . il by X, FUNCT_4:14
.= i by FUNCT_4:66 ;
IC S in dom (((IC S),il) --> (il1,I)) by A4, TARSKI:def 2;
then A6: IC u = (((IC S),il) --> (il1,I)) . (IC S) by FUNCT_4:14
.= il by COMPOS_1:3, FUNCT_4:66 ;
then IC (Following ((ProgramPart u),u)) = succ il by A1, A5;
hence x in { (IC (Exec (i,ss))) where ss is Element of product the Object-Kind of S : IC ss = il } by A3, A6, A5; :: thesis: verum
end;
now
assume x in { (IC (Exec (i,ss))) where ss is Element of product the Object-Kind of S : IC ss = il } ; :: thesis: x = succ il
then ex s being Element of product the Object-Kind of S st
( x = IC (Exec (i,s)) & IC s = il ) ;
hence x = succ il by A1; :: thesis: verum
end;
hence ( x in {(succ il)} iff x in { (IC (Exec (i,ss))) where ss is Element of product the Object-Kind of S : IC ss = il } ) by A2, TARSKI:def 1; :: thesis: verum
end;
hence NIC (i,il) = {(succ il)} by TARSKI:2; :: thesis: verum