Small types

Content created by Fredrik Bakke and Victor Blanchi.

Created on 2023-03-21.
Last modified on 2023-06-07.

module univalent-combinatorics.small-types where

open import foundation.small-types public
Imports 
open import elementary-number-theory.natural-numbers

open import foundation.dependent-pair-types
open import foundation.propositional-truncations
open import foundation.universe-levels

open import univalent-combinatorics.finite-types
open import univalent-combinatorics.standard-finite-types

Propositions

Every finite type is small.

is-small-Fin :
  (l : Level) → (k : ℕ) → is-small l (Fin k)
pr1 (is-small-Fin l k) = raise-Fin l k
pr2 (is-small-Fin l k) = compute-raise-Fin l k

is-small-is-finite :
  {l1 : Level} (l2 : Level) → (A : 𝔽 l1) → is-small l2 (type-𝔽 A)
is-small-is-finite l2 A =
  apply-universal-property-trunc-Prop
    ( is-finite-type-𝔽 A)
    ( is-small l2 (type-𝔽 A) , is-prop-is-small l2 (type-𝔽 A))
    ( λ p → is-small-equiv' (Fin (pr1 p)) (pr2 p) (is-small-Fin l2 (pr1 p)))

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