This problem assesses your ability to work with strings and handle various characters.

Here’s a Python implementation of the is_valid_palindrome function to determine if a given string is a palindrome:

def is_valid_palindrome(s: str) -> bool:
    """
    Determine if the given string is a palindrome.

    Parameters:
    - s: Input string.

    Returns:
    - bool: True if the string is a palindrome, False otherwise.
    """
    # Convert the string to lowercase and filter out non-alphanumeric characters
    cleaned_s = [char.lower() for char in s if char.isalnum()]

    # Check if the cleaned string is a palindrome
    return cleaned_s == cleaned_s[::-1]

# Example usage:

s = "AbcbA"
result = is_valid_palindrome(s)
print(result)  # Output: True

s = "A man, a plan, a canal: Panama"
result = is_valid_palindrome(s)
print(result)  # Output: True

s = "race a car"
result = is_valid_palindrome(s)
print(result)  # Output: False

s = ""
result = is_valid_palindrome(s)
print(result)  # Output: True

This solution converts the input string to lowercase and filters out non-alphanumeric characters. It then checks if the cleaned string reads the same forward and backward, indicating whether it is a palindrome.

Time Complexity:

The time complexity is O(n), where n is the length of the input string.

Space Complexity:

The space complexity is also O(n) due to the creation of the cleaned string.