3 \begin{enumerate}[label=(\alph*)]
5 \textbf{Map function:} for every tuple t in R and for every tuple t in
6 S, produce the key-value pair (t,t);\\
7 \textbf{Reduce funtion:} Receives input of the form (t; [t, t, …, t])\\
9 \textbf{Map function:} for every tuple t in R and for every tuple t in
10 S, produce the key-value pair (t; ''R'') or (t; ''S''), respectively.\\
11 \textbf{Reduce function:} Receives input of the form (t;
12 [x_{1},…,x_{n}]), where each x_{i} is either the form of ''R'' or
14 Outputs (t,t) if the input contains ''R'' but not ''S''.
15 Outputs nothing otherwise.\\