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- How to prove that a language is not regular? 10 answers
Question: ($B$ and $C$ are languages) $B$ is finite,$C$ isn't regular:
Prove/Disprove: $C\cup B$ isn't regular.
Thoughts: My intuition says this is true, but I need an idea to prove it. Since I don't know if $C$ as a CFG or RE language I don't know what kind of machine I can build for it.