let m be Nat; modSeq m,0 = NAT --> 0
set fm = modSeq m,0 ;
A1:
for x being set st x in dom (modSeq m,0 ) holds
(modSeq m,0 ) . x = (NAT --> 0 ) . x
proof
defpred S1[
Nat]
means (modSeq m,0 ) . $1
= 0 ;
let x be
set ;
( x in dom (modSeq m,0 ) implies (modSeq m,0 ) . x = (NAT --> 0 ) . x )
assume
x in dom (modSeq m,0 )
;
(modSeq m,0 ) . x = (NAT --> 0 ) . x
then reconsider x =
x as
Element of
NAT ;
(modSeq m,0 ) . 0 =
m mod 0
by Def2
.=
0
;
then A2:
S1[
0 ]
;
A3:
for
n being
Nat st
S1[
n] holds
S1[
n + 1]
by Th14, NAT_1:11;
for
n being
Nat holds
S1[
n]
from NAT_1:sch 2(A2, A3);
then
(modSeq m,0 ) . x = 0
;
hence
(modSeq m,0 ) . x = (NAT --> 0 ) . x
by FUNCOP_1:13;
verum
end;
dom (modSeq m,0 ) = NAT
by FUNCT_2:def 1;
hence
modSeq m,0 = NAT --> 0
by A1, Lm5, FUNCT_1:9; verum