deletions | additions       diff --git a/introduction_1.tex b/introduction_1.tex  index c75fda0..bbe2343 100644  --- a/introduction_1.tex  +++ b/introduction_1.tex 
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It is easy to show that   \begin{equation}  G_{\mu\nu}+ \Lambda g_{\mu\nu}=\frac{8 \pi G}{c^4}T_{\mu\nu}  \end{equation}