diff --git a/sheet05/a1/explanation.txt b/sheet05/a1/explanation.txt
index e69de29..1c204bc 100644
--- a/sheet05/a1/explanation.txt
+++ b/sheet05/a1/explanation.txt
@@ -0,0 +1,6 @@
+UNIX permissions only support one Owner, one Group, and Other (UGO). 
+The 'Group' slot is already taken by the specific lecture group to give students write access.
+If we use 'Other' to give the supervisor read access, every user on the system could read it, which would violate the requirements.
+If we add the supervisor to the lecture group, they get write access, which also violates the requirements.
+
+Because a file cannot have multiple groups or user-specific overrides under standard UNIX permissions, this cannot be solved.
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