I'm Sean. I'll make a more complete user page sometime in the future.
∀ ε > 0 , ∃ δ > 0 {\displaystyle \forall \varepsilon >0,\exists \delta >0} such that ∀ x , | x − a | < δ → | f ( x ) − L | < ε {\displaystyle \forall x,\vert x-a\vert <\delta \rightarrow \vert f(x)-L\vert <\varepsilon }