Designations Big-O and Omega

Question

I read this question the definition of Big-O notation .
But I have less than 50 reviews, so I hope someone helps me.

My question about this sentence:

There are many algorithms for which there is no unique function g such that complexity is both O (g) and Ω (g). For example, insertion sorting has a lower bound On () that cannot find anything less than n², and an upper bound Ω from Ω (n).

for large n, O (n²) is the upper boundary, and Ω (n) is the lower boundary, or maybe I misunderstood? can someone help me?

Answer 1

has a lower boundary Big-O O (n²)

, ( big-O ), , , :

Big-O - .

f(n) ϵ O(g(n)) , |f(n)| <= k|g(n)| n ( ).

, , f(n) = n2 (, , ). n2 ϵ O(n2), n2 ϵ O(n3) n2 ϵ O(n4) n2 ϵ O(n5) ....

, g(n), , n2.

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, , - , , , .

. , .

Answer 2

, ?

, .

Big-O big-Ω .

Insertion , O (n ²). Ω (n) .

_{, .}