deletions | additions       diff --git a/paragraph_2_Mimic_the_derivation__.tex b/paragraph_2_Mimic_the_derivation__.tex  index 8aec383..b240074 100644  --- a/paragraph_2_Mimic_the_derivation__.tex  +++ b/paragraph_2_Mimic_the_derivation__.tex 
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$$ $$\\ \forall \phi \in C_{0}^{1}(\mathbb{R}^2 $$  If u is a weak solution, x =\varepsilon (t), then u must satisfy the condition  \[  \frac{f(u^{-} - f(u^{+}}{u^{-} - u^{+}} = \varepsilon'(t) \]