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theory Propositions
imports
  MLTT.Prelude
  Equivalence

begin

definition isProp where "isProp A ≡ ∏x y: A. x =⇘A⇙ y"
definition isSet where "isSet A ≡ ∏x y: A. ∏p q: x =⇘A⇙ y. p =⇘x =⇘A⇙ y⇙ q"

Theorem isProp_Top: "isProp ⊤"
  unfolding isProp_def
  by (intros, elims, refl)

Theorem isProp_Bot: "isProp ⊥"
  unfolding isProp_def
  by (intros, elim)

end