結合の法則

$\displaystyle x \lor (y \lor z)$	$\textstyle =$	$\displaystyle (x \lor y) \lor z$	(49)
$\displaystyle x \land (y \land z)$	$\textstyle =$	$\displaystyle (x \land y) \land z$	(50)
$\displaystyle x \cdot (y \cdot z)$	$\textstyle =$	$\displaystyle (x \cdot y) \cdot z$	(51)
$\displaystyle x (y z)$	$\textstyle =$	$\displaystyle (x y) z$	(52)