(* *)
(**************************************************************************)
+include "ground_2/xoa/ex_1_4.ma".
include "static_2/notation/relations/simple_1.ma".
include "static_2/syntax/term.ma".
* /2 width=2 by ex_intro/
#p #I #V #T #H elim (simple_inv_bind … H)
qed-.
+
+(* Basic properties *********************************************************)
+
+lemma simple_dec_ex (X): ∨∨ 𝐒⦃X⦄ | ∃∃p,I,T,U. X = ⓑ{p,I}T.U.
+* [ /2 width=1 by simple_atom, or_introl/ ]
+* [| /2 width=1 by simple_flat, or_introl/ ]
+/3 width=5 by ex1_4_intro, or_intror/
+qed-.