let O be non empty connected Poset; for R being array of O holds inversions R c= [:(dom R),(dom R):]
let R be array of O; inversions R c= [:(dom R),(dom R):]
let x be object ; TARSKI:def 3 ( not x in inversions R or x in [:(dom R),(dom R):] )
assume A1:
x in inversions R
; x in [:(dom R),(dom R):]
then consider a, b being Element of dom R such that
A2:
( x = [a,b] & a in b & R /. a > R /. b )
;
( a in dom R & b in dom R )
by A2, A1, Th46;
hence
x in [:(dom R),(dom R):]
by A2, ZFMISC_1:def 2; verum