field R2 = X
by ORDERS_1:12;
then A1:
R2 is_reflexive_in X
by RELAT_2:def 9;
let R be Relation of X; ( R = R1 \, R2 implies ( R is total & R is reflexive ) )
assume A2:
R = R1 \, R2
; ( R is total & R is reflexive )
thus A3:
R is total
R is reflexive
then A5:
field R = X
by ORDERS_1:12;
let x be object ; RELAT_2:def 1,RELAT_2:def 9 ( not x in field R or [x,x] in R )
assume A6:
x in field R
; [x,x] in R
then reconsider x = x as Element of X by A3, ORDERS_1:12;
[x,x] in R2
by A6, A5, A1;
then
( x,x in R1 or ( not x,x in R1 & x,x in R2 ) )
;
then
x,x in R
by A2, Th9;
hence
[x,x] in R
; verum