set R = LatOrder L;
for x, y, z being object st [x,y] in LatOrder L & [y,z] in LatOrder L holds
[x,z] in LatOrder L
proof
let x,
y,
z be
object ;
( [x,y] in LatOrder L & [y,z] in LatOrder L implies [x,z] in LatOrder L )
assume A1:
(
[x,y] in LatOrder L &
[y,z] in LatOrder L )
;
[x,z] in LatOrder L
then consider x1,
y1 being
object such that A2:
(
[x,y] = [x1,y1] &
x1 in the
carrier of
L &
y1 in the
carrier of
L )
by RELSET_1:2;
consider y2,
z2 being
object such that A3:
(
[y,z] = [y2,z2] &
y2 in the
carrier of
L &
z2 in the
carrier of
L )
by A1, RELSET_1:2;
reconsider xx =
x,
yy =
y,
zz =
z as
Element of
L by A2, A3, XTUPLE_0:1;
(
xx [= yy &
yy [= zz )
by A1, OrdLat;
then
xx [= zz
by TransLat;
hence
[x,z] in LatOrder L
;
verum
end;
hence
LatOrder L is transitive
by RELAT_2:31; verum