交換の法則

$\displaystyle x \lor y$	$\textstyle =$	$\displaystyle y \lor x$	(46)
$\displaystyle x \land y$	$\textstyle =$	$\displaystyle y \land x$	(47)
$\displaystyle xy$	$\textstyle =$	$\displaystyle yx$	(48)