Hey we know that relational algebra is domain independent but going into theoretical How to prove relational algebra as domain independent ,can we do it by induction if so how.. ??

Well, I am going to make the wild assumption that this is for some class. That being the case, what is the definition (from the book) of domain independence? Proofs at the beginning of the year usually flow from the definitions.

One of my college profs gave one extra credit question on every essay test that required "thinking outside the box" which I loved. I was the only student in his teaching history to score points on every one of those questions.

Your "Induction" reference reminds me of his first "thinking outside the box" question, which was "Define the Universe. Give three examples."

-PatP

and one counterexample

I was in a great books program in college. No textbooks. All primary sources. Most classes involved papers or essay exams. High points were always given for turning the question on it's head or questioning it's validity.