add proof

felixpernegger · web-flow · commit 611e05074a31 · 2026-04-03T22:30:43.000+02:00
diff --git a/theorems/T000001.md b/theorems/T000001.md
@@ -4,9 +4,6 @@ if:
   P000016: true
 then:
   P000019: true
-refs:
-- zb: "0386.54001"
-  name: Counterexamples in Topology
 ---
 
-Asserted on page 21 of {{zb:0386.54001}}.
+Immediate from the definitions.
