let s be SCM-State; for t being Element of SCM-Data-Loc
for u being Integer holds (SCM-Chg (s,t,u)) . NAT = s . NAT
let t be Element of SCM-Data-Loc ; for u being Integer holds (SCM-Chg (s,t,u)) . NAT = s . NAT
let u be Integer; (SCM-Chg (s,t,u)) . NAT = s . NAT
A1:
{t} = dom (t .--> u)
by FUNCOP_1:13;
( SCM-OK . NAT = NAT & SCM-OK . t = INT )
by Lm5, Th7, Th8;
then
not NAT in dom (t .--> u)
by A1, NUMBERS:27, TARSKI:def 1;
hence
(SCM-Chg (s,t,u)) . NAT = s . NAT
by FUNCT_4:11; verum