let R be Relation; :: thesis: ( R is connected implies R ~ is connected )
assume A1:
for x, y being set st x in field R & y in field R & x <> y & not [x,y] in R holds
[y,x] in R
; :: according to RELAT_2:def 6,RELAT_2:def 14 :: thesis: R ~ is connected
A2:
field R = field (R ~ )
by RELAT_1:38;
let x be set ; :: according to RELAT_2:def 6,RELAT_2:def 14 :: thesis: for b1 being set holds
( not x in field (R ~ ) or not b1 in field (R ~ ) or x = b1 or [x,b1] in R ~ or [b1,x] in R ~ )
let y be set ; :: thesis: ( not x in field (R ~ ) or not y in field (R ~ ) or x = y or [x,y] in R ~ or [y,x] in R ~ )
assume
( x in field (R ~ ) & y in field (R ~ ) & x <> y )
; :: thesis: ( [x,y] in R ~ or [y,x] in R ~ )
then
( [x,y] in R or [y,x] in R )
by A1, A2;
hence
( [x,y] in R ~ or [y,x] in R ~ )
by RELAT_1:def 7; :: thesis: verum