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-rw-r--r--Prod.thy19
1 files changed, 19 insertions, 0 deletions
diff --git a/Prod.thy b/Prod.thy
index 445ddd8..fbea4df 100644
--- a/Prod.thy
+++ b/Prod.thy
@@ -69,4 +69,23 @@ abbreviation Function :: "[Term, Term] \<Rightarrow> Term" (infixr "\<rightarro
where "A \<rightarrow> B \<equiv> \<Prod>_:A. B"
+section \<open>Unit type\<close>
+
+axiomatization
+ Unit :: Term ("\<one>") and
+ pt :: Term ("\<star>") and
+ indUnit :: "[Typefam, Term, Term] \<Rightarrow> Term"
+where
+ Unit_form: "\<one> : U(0)"
+and
+ Unit_intro: "\<star> : \<one>"
+and
+ Unit_elim: "\<And>i C c a. \<lbrakk>C: \<one> \<longrightarrow> U(i); c : C \<star>; a : \<one>\<rbrakk> \<Longrightarrow> indUnit C c a : C a"
+and
+ Unit_comp: "\<And>i C c. \<lbrakk>C: \<one> \<longrightarrow> U(i); c : C \<star>\<rbrakk> \<Longrightarrow> indUnit C c \<star> \<equiv> c"
+
+lemmas Unit_rules [intro] = Unit_form Unit_intro Unit_elim Unit_comp
+lemmas Unit_comps [comp] = Unit_comp
+
+
end \ No newline at end of file