stdSimplex — Mathlib

English

If S is representable, the corresponding face is represented by δ and hence Δ[m].

Русский

Если грань представима, соответствующая δ и Δ[m] представляются.

LaTeX

$$faceRepresentableBy {n} (S) {m} (e) …$$

Lean4

/-- The functor which sends `⦋n⦌` to the simplicial set `Δ[n]` equipped by
the obvious augmentation towards the terminal object of the category of sets. -/
@[simps]
noncomputable def stdSimplex : SimplexCategory ⥤ SSet.Augmented.{u}
    where
  obj
    Δ :=
    { left := SSet.stdSimplex.obj Δ
      right := terminal _
      hom := { app := fun _ => terminal.from _ } }
  map
    θ :=
    { left := SSet.stdSimplex.map θ
      right := terminal.from _ }

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