let G be non empty good 1-sorted ; for s being SCM-State of G
for t being Element of SCM-Data-Loc
for u being Element of G holds (SCM-Chg (s,t,u)) . NAT = s . NAT
let s be SCM-State of G; for t being Element of SCM-Data-Loc
for u being Element of G holds (SCM-Chg (s,t,u)) . NAT = s . NAT
let t be Element of SCM-Data-Loc ; for u being Element of G holds (SCM-Chg (s,t,u)) . NAT = s . NAT
let u be Element of G; (SCM-Chg (s,t,u)) . NAT = s . NAT
A1:
( NAT <> the carrier of G & {t} = dom (t .--> u) )
by Def2, FUNCOP_1:13;
( (SCM-OK G) . NAT = NAT & (SCM-OK G) . t = the carrier of G )
by Th2, Th3, AMI_2:22;
then
not NAT in dom (t .--> u)
by A1, TARSKI:def 1;
hence
(SCM-Chg (s,t,u)) . NAT = s . NAT
by FUNCT_4:11; verum