let m be Element of NAT ; not SubstPoset NAT ,{m} is complete
reconsider Cos = {(PFArt 1,m)} as Element of by Th31;
assume
SubstPoset NAT ,{m} is complete
; contradiction
then consider a being Element of such that
A1:
PFDrt m is_>=_than a
and
A2:
for b being Element of st PFDrt m is_>=_than b holds
a >= b
by LATTICE5:def 2;
SubstitutionSet NAT ,{m} = the carrier of (SubstPoset NAT ,{m})
by SUBSTLAT:def 4;
then
a in SubstitutionSet NAT ,{m}
;
then reconsider a' = a as Element of Fin (PFuncs NAT ,{m}) ;
set Mi = Involved a';
PFDrt m is_>=_than Cos
then
a <> {}
by A2, Th42;
then reconsider Mi = Involved a' as non empty finite Subset of by A1, Th37, Th43;
reconsider mX = (max Mi) + 1 as non empty Element of NAT ;
reconsider Sum = {(PFArt mX,m)} as Element of by Th31;
set b = a "\/" Sum;
Sum is_<=_than PFDrt m
then A10:
PFDrt m is_>=_than a "\/" Sum
by A1, Th34;
A11:
a <> a "\/" Sum
a <= a "\/" Sum
by YELLOW_0:22;
then
a < a "\/" Sum
by A11, ORDERS_2:def 10;
hence
contradiction
by A2, A10, ORDERS_2:30; verum