1 expression
1.1  = 
1.1  <> 
1.1  < 
1.1  > 
1.1  <= 
1.1  >= 
1.2 (1) 

1.3 SOME
1.3 ANY
1.3 ALL
1.4 ( fullselect )
1 ( row-value-expression )  = 
1.1 SOME
1.1 ANY
1.1.1 ( fullselect )
1 ( row-value-expression )  <>  ALL ( fullselect )