digraph lambda_sub_cfg {
  rankdir=TB;
  bgcolor="transparent";
  node [fontname=Inter, fontsize=10, fontcolor="#c9d1bb"];
  edge [fontname=Inter, fontsize=9, color="#8f9780", fontcolor="#c9d1bb"];
  start [label="term", shape=oval, style=filled, fillcolor="transparent", color="#a9b492"];
  beta [label="(lambda x. t) u", shape=box, style="rounded,filled", fillcolor="transparent", color="#a9b492", fontcolor="#c9d1bb"];
  es [label="t[x/u]", shape=box, style="rounded,filled", fillcolor="transparent", color="#a9b492", fontcolor="#c9d1bb"];
  pure [label="pure term", shape=oval, style=filled, fillcolor="transparent", color="#a9b492"];
  nf [label="normal form", shape=doublecircle, style=filled, fillcolor="#2a3a22", color="#8fb071"];
  start -> beta [label="App(Lam,_)"];
  start -> es [label="ESub"];
  start -> pure [label="BVar/FVar/Lam"];
  beta -> es [label="B", color="#dfe7cc"];
  es -> es [label="R (one occurrence)", color="#a9b492"];
  es -> pure [label="Gc (x not in fv)", color="#8fb071"];
  pure -> pure [label="B under context", color="#dfe7cc"];
  es -> nf [label="R/Gc normalisation", color="#a9b492"];
}