Let $\{(X_{i},Y_{i})\}^\infty_{i=1}$ be a |DMS with common pmf $p_{XY}$ on $\mathcal{X}\times\mathcal{Y}$. Given $\delta>0$ and integer $n\ge1$, the jointly typical set $A_\delta^{(n)}$ (or jointly $\delta$ -typical set) with respect to the source is $$\begin{align*} A_{\delta}^{(n)}=\left\{(x^{n},y^{n})\in \mathcal{X}^{n}\times\mathcal{Y}^{n}:\left|-\frac{1}{n}\log_{2}(p_{X^{n}}(x^{n}))-H(X)\right|\le\delta,\right.\\ \left|-\frac{1}{n}\log_{2}(p_{Y^{n}}(y^{n}))-H(Y)\right|\le\delta,\\ \left.\left|-\frac{1}{n}\log_{2}(p_{X^{n}Y^{n}}(x^{n},y^{n}))-H(X,Y)\right|\le\delta \right\}\\ \end{align*}$$