\documentclass[border=10pt]{standalone}  \usepackage[utf8]{inputenc} \usepackage{amsmath} \usepackage{amssymb}  \usepackage{tikz} \usetikzlibrary{shapes,arrows}  \everymath{\displaystyle}  \begin{document} \tikzstyle{decision} = [diamond, draw, fill=yellow!20,   aspect=2, text badly centered, inner sep=0pt]  \tikzstyle{block} = [rectangle, draw, fill=blue!20,   text centered, rounded corners]  \tikzstyle{convergence} = [rectangle, draw, fill=green!20,   node distance=8cm, text centered, rounded corners]  \tikzstyle{divergence} = [rectangle, draw, fill=red!20,   node distance=8cm, text centered, rounded corners]    \tikzstyle{line} = [-stealth, thick, draw]  \begin{tikzpicture}[node distance=4cm, auto, text width=12em]   \node [block] (init) {Calculate $\left|\frac{a_{k+1}}{a_k}\right|$};   \node [decision, below of=init, node distance=3cm] (case1) {Is $\limsup_{k\to\infty} \left|\frac{a_{k+1}}{a_k}\right| < 1$?};   \node [decision, below of=case1] (case2) {Is $\liminf_{k\to\infty} \left|\frac{a_{k+1}}{a_k}\right| > 1$?};   \node [decision, below of=case2] (case3) {Is $\left|\frac{a_{k+1}}{a_k}\right| \ge 1$ for almost all $k\in\mathbb N$?};   \node [convergence, right of=case1] (yes1) {$\sum_{k=1}^\infty a_k$ converges absolutely};   \node [divergence, right of=case2] (no2) {$\sum_{k=1}^\infty a_k$ diverges};   \node [divergence, right of=case3] (no3) {$\sum_{k=1}^\infty a_k$ diverges};   \node [block, below of=case3, node distance=3.5cm] (final) {The ratio test cannot be applied};   \path [line] (init) edge (case1);   \path [line] (case1) -- node [xshift=5em] {Yes} (yes1);   \path [line] (case2) -- node [xshift=5em] {Yes} (no2);   \path [line] (case3) -- node [xshift=5em] {Yes} (no3);   \path [line] (case1) -- node {No} (case2);   \path [line] (case2) -- node {No} (case3);   \path [line] (case3) -- node {No} (final); \end{tikzpicture}  \end{document}