Update header.tex

Author: khanh101

assets/header.tex

@@ -77,6 +77,7 @@
 \DeclareMathOperator{\id}{id}
 \DeclareMathOperator{\Var}{Var}
 \DeclareMathOperator{\Cov}{Cov}
+\DeclareMathOperator{\RV}{RV}
 
 %% pair delimiter
 \DeclarePairedDelimiter{\abs}{\lvert}{\rvert}