Contradiction in Cormen regarding Insertion sort

Question

In Cormen theorem 3.1 says that

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For example, the best case running time of insertion sort is big-omega(n),

Answer 1

There is no contradiction here. The question only states to prove that Big-Theta(g(n)) is asymptotically tightly bound by Big-O(g(n)) and Big-Omega(g(n)). If you prove the question, you only prove that a function runs in Big-Theta(g(n)) if and only if it runs between Big-O(g(n)) and Big-Omega(g(n)).

The insertion sort runs from Big-Omega(n) to Big-Oh(n^2), so the running time of insertion sort CANNOT be tightly bound to Big-Theta(n^2).

As a matter of fact, CLRS never uses Big-Theta(n^2) to tightly bound insertion sort.