<?php
$a = array(true,false);
$b = array(true,false);

for ($i=0;$i<count($a);$i++) {
        for ($j=0;$j<count($b);$j++) {
                echo "\$a is ".out($a[$i])." and ";
                echo "\$b is ".out($b[$j])."\n";
                echo "(!\$a && !\$b) is ".out((!$a[$i] && !$b[$j]))."\n";
                echo "(!(\$a || \$b)) is ".out((!($a[$i] || $b[$j])))."\n";
                echo "(!(\$a && \$b)) is ".out((!($a[$i] && $b[$j])))."\n";
                echo "(!\$a || !\$b) is ".out((!$a[$i] || !$b[$j]))."\n";
        }
}

function out($v) {
        return $v?"true":"false";
}

?>
/*
~$ php logic.php
$a is true and $b is true
(!$a && !$b) is false
(!($a || $b)) is false
(!($a && $b)) is false
(!$a || !$b) is false
$a is true and $b is false
(!$a && !$b) is false
(!($a || $b)) is false
(!($a && $b)) is true
(!$a || !$b) is true
$a is false and $b is true
(!$a && !$b) is false
(!($a || $b)) is false
(!($a && $b)) is true
(!$a || !$b) is true
$a is false and $b is false
(!$a && !$b) is true
(!($a || $b)) is true
(!($a && $b)) is true
(!$a || !$b) is true
*/