“!” Comparison Issues

$var1 = 6;
$var2 = true;
$var3 = false;
$var4 = 7;
var_dump($var1) = 6;
var_dump(!$var1) = false;
var_dump($var1 > $var4) = false;
var_dump(!$var1 > $var4) = false;
var_dump(!($var1 > $var4)) = true;