From 44d467e58966792c19f363d769906ac5586d9937 Mon Sep 17 00:00:00 2001
From: Chloe Brown <chloe.brown.00@outlook.com>
Date: Sat, 1 Apr 2023 14:57:53 +0100
Subject: Prove composition preserves IsNotId.

---
 src/Core/Thinning.idr | 6 ++++++
 1 file changed, 6 insertions(+)

(limited to 'src')

diff --git a/src/Core/Thinning.idr b/src/Core/Thinning.idr
index ecc3f47..7ef2562 100644
--- a/src/Core/Thinning.idr
+++ b/src/Core/Thinning.idr
@@ -175,3 +175,9 @@ compAssoc :
   (thin1 : sx `Thins` sy) ->
   thin3 . (thin2 . thin1) = (thin3 . thin2) . thin1
 compAssoc thin3 thin2 thin1 = compAssoc' (view thin3) (view thin2) (view thin1)
+
+-- Non-Identities
+
+export
+compPresNotId : IsNotId thin2 -> IsNotId thin1 -> IsNotId (thin2 . thin1)
+compPresNotId ItIsThinner ItIsThinner = ItIsThinner
-- 
cgit v1.2.3