digraph techviz {
  graph [rankdir=LR, splines=ortho, nodesep=0.55, ranksep=0.85];
  node [fontname=Helvetica, fontsize=11, margin="0.18,0.12", style="rounded,filled", fillcolor=white, color="#2d4357", penwidth=1.5];
  edge [fontname=Helvetica, fontsize=10, color="#364b5f", penwidth=1.4, arrowsize=0.75];
  n0 [label="AP1 → AP2", shape=box, style="rounded,filled"];
  n1 [label="AP2 → AP3", shape=box, style="rounded,filled"];
  n2 [label="AP3 → AP4", shape=box, style="rounded,filled"];
  n3 [label="AP4 → AP3", shape=box, style="rounded,filled"];
}