let S, T be non empty reflexive antisymmetric up-complete RelStr ; :: thesis: for x being Element of [:S,T:] holds
( proj1 (wayabove x) c= wayabove (x `1 ) & proj2 (wayabove x) c= wayabove (x `2 ) )
let x be Element of [:S,T:]; :: thesis: ( proj1 (wayabove x) c= wayabove (x `1 ) & proj2 (wayabove x) c= wayabove (x `2 ) )
A1:
the carrier of [:S,T:] = [:the carrier of S,the carrier of T:]
by YELLOW_3:def 2;
then A2:
x = [(x `1 ),(x `2 )]
by MCART_1:23;
let b be set ; :: according to TARSKI:def 3 :: thesis: ( not b in proj2 (wayabove x) or b in wayabove (x `2 ) )
assume
b in proj2 (wayabove x)
; :: thesis: b in wayabove (x `2 )
then consider a being set such that
A4:
[a,b] in wayabove x
by RELAT_1:def 5;
reconsider b' = b as Element of T by A1, A4, ZFMISC_1:106;
reconsider a = a as Element of S by A1, A4, ZFMISC_1:106;
[a,b'] >> x
by A4, WAYBEL_3:8;
then
b' >> x `2
by A2, Th18;
hence
b in wayabove (x `2 )
; :: thesis: verum