Girard のパラドックスの説明に使った証明に図を添付する

[Seasawher]

可換図式をいい感じに Typst で生成する例

#import "@preview/fletcher:0.5.8" as fletcher: diagram, edge

#set page(
  width: auto,
  height: auto,
  margin: 4mm,
)

#set text(size: 13pt)

#diagram(
    cell-size: 30mm,
    spacing: (38mm, 24mm),
    edge-stroke: 0.75pt,
    node-outset: 5pt,
    mark-scale: 80%,
    $
      sum_(a : alpha) beta(a) edge("r", "=", label: "id") & T \
      beta(x) edge("u", "->", label: "単射") edge("r", "=", label: "id") & op("Set") T edge("u", "->", label: "単射")
    $
)