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+theory Propositions
+imports
+ MLTT.Prelude
+ Equivalence
+
+begin
+
+definition isProp where "isProp A \<equiv> \<Prod>x y: A. x =\<^bsub>A\<^esub> y"
+definition isSet where "isSet A \<equiv> \<Prod>x y: A. \<Prod>p q: x =\<^bsub>A\<^esub> y. p =\<^bsub>x =\<^bsub>A\<^esub> y\<^esub> q"
+
+Theorem isProp_Top: "isProp \<top>"
+ unfolding isProp_def
+ by (intros, elims, refl)
+
+Theorem isProp_Bot: "isProp \<bottom>"
+ unfolding isProp_def
+ by (intros, elim)
+
+end