#import "@preview/fletcher:0.6.0" as fletcher: diagram, node, edge

#let hom = edge.with(in-math: true)

#diagram(
spacing: (1em, 3em),
$
& tau^* (bold(A B)^n R slash.double R^times) hom(->) &
bold(B)^n R slash.double R^times \
X hom("ur", "-->") hom("=") &
X hom(->, tau) hom("u", <-) &
bold(B) R^times hom("u", <-)
$,
edge((0,1), "d,rr,u", "->>", text(blue, $Gamma^*_R$),
stroke: blue, label-side: center)
)