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Question

This answer was invalid and I do not know why. Thanks for your help in advance.
c) Regular Grammar 3

Konstruieren Sie eine rechtsreguläre Grammatik für die folgende Sprache: L = {w ∈ {a,b}^* | w has at least one occurrence of the substring aba}
S -> abaA | aS | bS
A -> b | 

Answer 1

Your grammar describes the language waba + wabab where w is any word consisting of letters a and b. So, the occurrence of aba is not at an arbitrary place within the word.

Why not the following?

S -> aS | bS | A
A -> abaB
B -> aB | bB |