Kleeneliness is next to Gödeliness

# Lemma

Given **L** a CF language `then`

∃ n∈**N**,
n constant `so that`

∀ z∈L, |z|≥n so that we can decompose z=uvwxy `so that`

1 |vwx|≤n
2 |vx|>0
3 ∀ i≥0 we have that uvⁱwxⁱy∈L

# Usage

One uses the lemma to prove that a language **is not** CF, to do so one must show, that fixed an arbitrary n
arbitrary, ∃ zⁱwxⁱy∉L \ |z\≥n but `so that`

for every possible decomposition such as uvwxy, with 1. and 2. constraints uvⁱwxⁱy∉L for some i≥0