let R be Relation; for X being set holds
( ( R |_2 X is transitive implies R is_transitive_in X ) & ( R |_2 X is antisymmetric implies R is_antisymmetric_in X ) )
let X be set ; ( ( R |_2 X is transitive implies R is_transitive_in X ) & ( R |_2 X is antisymmetric implies R is_antisymmetric_in X ) )
set R2 = R |_2 X;
A1:
R |_2 X = R /\ [:X,X:]
by WELLORD1:def 6;
hereby ( R |_2 X is antisymmetric implies R is_antisymmetric_in X )
assume A2:
R |_2 X is
transitive
;
R is_transitive_in Xnow for x, y, z being object st x in X & y in X & z in X & [x,y] in R & [y,z] in R holds
[x,z] in Rlet x,
y,
z be
object ;
( x in X & y in X & z in X & [x,y] in R & [y,z] in R implies [x,z] in R )assume A3:
(
x in X &
y in X &
z in X &
[x,y] in R &
[y,z] in R )
;
[x,z] in Rthen
(
[x,y] in [:X,X:] &
[y,z] in [:X,X:] )
by ZFMISC_1:87;
then A4:
(
[x,y] in R |_2 X &
[y,z] in R |_2 X )
by A3, A1, XBOOLE_0:def 4;
then
(
x in field (R |_2 X) &
y in field (R |_2 X) &
z in field (R |_2 X) )
by RELAT_1:15;
then
[x,z] in R |_2 X
by A4, A2, RELAT_2:def 16, RELAT_2:def 8;
hence
[x,z] in R
by A1, XBOOLE_0:def 4;
verum end; hence
R is_transitive_in X
by RELAT_2:def 8;
verum
end;
assume A5:
R |_2 X is antisymmetric
; R is_antisymmetric_in X
now for x, y being object st x in X & y in X & [x,y] in R & [y,x] in R holds
x = ylet x,
y be
object ;
( x in X & y in X & [x,y] in R & [y,x] in R implies x = y )assume A6:
(
x in X &
y in X &
[x,y] in R &
[y,x] in R )
;
x = ythen
(
[x,y] in [:X,X:] &
[y,x] in [:X,X:] )
by ZFMISC_1:87;
then A7:
(
[x,y] in R |_2 X &
[y,x] in R |_2 X )
by A6, A1, XBOOLE_0:def 4;
then
(
x in field (R |_2 X) &
y in field (R |_2 X) )
by RELAT_1:15;
hence
x = y
by A7, A5, RELAT_2:def 12, RELAT_2:def 4;
verum end;
hence
R is_antisymmetric_in X
by RELAT_2:def 4; verum