What are the relational operators in Pig?

In Pig, there are several types of relational operators.

1. == : equals to
2. !=: not equal to
3. Less than
4. <= : less than or equal to
5. greater than
6. = greater than or equal to
7. matches: used for pattern matching in regular expressions
8. Check if it is empty.
9. is not empty: to determine if it is not empty
10. Check if it is an empty string.
11. Check if the string is not empty.