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+(*  Title:  HoTT/Unit.thy
+    Author: Josh Chen
+
+Unit type
+*)
+
+theory Unit
+  imports HoTT_Base
+begin
+
+
+section \<open>Constants and type rules\<close>
+
+axiomatization
+  Unit :: Term  ("\<one>") and
+  pt :: Term    ("\<star>") and
+  indUnit :: "[Term, Term] \<Rightarrow> Term"  ("(1ind\<^sub>\<one>)")
+where
+  Unit_form: "\<one>: U(O)"
+and
+  Unit_intro: "\<star>: \<one>"
+and
+  Unit_elim: "\<lbrakk>C: \<one> \<longrightarrow> U(i); c: C(\<star>); a: \<one>\<rbrakk> \<Longrightarrow> ind\<^sub>\<one>(c)(a) : C(a)"
+and
+  Unit_comp: "\<lbrakk>C: \<one> \<longrightarrow> U(i); c: C(\<star>)\<rbrakk> \<Longrightarrow> ind\<^sub>\<one>(c)(\<star>) \<equiv> c"
+
+
+text "Rule attribute declarations:"
+
+lemmas Unit_comp [comp]
+lemmas Unit_routine [intro] = Unit_form Unit_intro Unit_elim
+
+end