How can the logical implications of a PHP expression be determined and validated?

To determine and validate the logical implications of a PHP expression, you can use conditional statements such as if, else if, and else. By setting up different conditions based on the logical implications you want to test, you can control the flow of your program and execute different code blocks accordingly.

// Example PHP code snippet to determine and validate logical implications
$age = 25;

if ($age < 18) {
    echo "You are a minor.";
} elseif ($age >= 18 && $age < 65) {
    echo "You are an adult.";
} else {
    echo "You are a senior citizen.";
}