let N be non empty with_non-empty_elements set ; for S being non empty IC-Ins-separated halting weakly_standard AMI-Struct of N holds (il. (S,0)) .--> (halt S) is really-closed
let S be non empty IC-Ins-separated halting weakly_standard AMI-Struct of N; (il. (S,0)) .--> (halt S) is really-closed
reconsider F = (il. (S,0)) .--> (halt S) as NAT -defined the Instructions of S -valued finite Function ;
let l be Element of NAT ; AMISTD_1:def 9 ( not l in dom ((il. (S,0)) .--> (halt S)) or NIC ((((il. (S,0)) .--> (halt S)) /. l),l) c= dom ((il. (S,0)) .--> (halt S)) )
assume A1:
l in dom ((il. (S,0)) .--> (halt S))
; NIC ((((il. (S,0)) .--> (halt S)) /. l),l) c= dom ((il. (S,0)) .--> (halt S))
A2:
dom F = {(il. (S,0))}
by FUNCOP_1:13;
then A3:
l = il. (S,0)
by A1, TARSKI:def 1;
F /. l =
F . l
by A1, PARTFUN1:def 6
.=
halt S
by A3, FUNCOP_1:72
;
hence
NIC ((((il. (S,0)) .--> (halt S)) /. l),l) c= dom ((il. (S,0)) .--> (halt S))
by A2, A3, AMISTD_1:2; verum