Given a function whose graph is #92;#123;(1,7),(2,5),(3,3),(4,3),(5,2),(6,4),(7,6),(8,5),(9,7),(10,6),(11,6)#92;#125;, append an apostrophe to the abscissas so that they will not be confused with ordinates when obtaining their disjoint union, which is: #92;#123;2,3,4,5,6,7,1',2',3',4',5',6',7',8',9',10',11'#92;#125;. The cograph then is #92;#123;#92;#123;7,1',9'#92;#125;,#92;#123;6,7',10',11'#92;#125;,#92;#123;5,2',8'#92;#125;,#92;#123;4,6'#92;#125;,#92;#123;3,3',4'#92;#125;,#92;#123;2,5'#92;#125;#92;#125;.
Source: wiktionary