let R1, R2 be LATTICE; for X being set st RelStr(# the carrier of R1, the InternalRel of R1 #) = RelStr(# the carrier of R2, the InternalRel of R2 #) holds
for p1 being Element of R1
for p2 being Element of R2 st p1 = p2 & X is_>=_than p1 holds
X is_>=_than p2
let X be set ; ( RelStr(# the carrier of R1, the InternalRel of R1 #) = RelStr(# the carrier of R2, the InternalRel of R2 #) implies for p1 being Element of R1
for p2 being Element of R2 st p1 = p2 & X is_>=_than p1 holds
X is_>=_than p2 )
assume A1:
RelStr(# the carrier of R1, the InternalRel of R1 #) = RelStr(# the carrier of R2, the InternalRel of R2 #)
; for p1 being Element of R1
for p2 being Element of R2 st p1 = p2 & X is_>=_than p1 holds
X is_>=_than p2
let p1 be Element of R1; for p2 being Element of R2 st p1 = p2 & X is_>=_than p1 holds
X is_>=_than p2
let p2 be Element of R2; ( p1 = p2 & X is_>=_than p1 implies X is_>=_than p2 )
assume that
A2:
p1 = p2
and
A3:
X is_>=_than p1
; X is_>=_than p2
let b2 be Element of R2; LATTICE3:def 8 ( not b2 in X or p2 <= b2 )
reconsider b1 = b2 as Element of R1 by A1;
assume
b2 in X
; p2 <= b2
then
p1 <= b1
by A3, LATTICE3:def 8;
hence
p2 <= b2
by A1, A2, Lm1; verum