Math — Polya's Problem Solving

digraph Polya {
  node [shape=box, style=rounded];
  "Understand the problem" -> "Devise a plan";
  "Devise a plan" -> "Carry out the plan";
  "Carry out the plan" -> "Look back / check";
  "Look back / check" -> "Understand the problem" [label="refine", style=dashed];
}