instance fixed

diff --git a/helm/software/matita/nlibrary/topology/igft.ma b/helm/software/matita/nlibrary/topology/igft.ma
index 06c492e86236b6d951e942f8cf991a3eecc9d612..d6043fba2c1d413fc22626fd567e18dbc34c5779 100644 (file)
--- a/helm/software/matita/nlibrary/topology/igft.ma
+++ b/helm/software/matita/nlibrary/topology/igft.ma
@@ -1168,7 +1168,7 @@ We now proceed with the proof of the infinity rule.
 
 D*)
 
-alias symbol "covers" = "new covers set".
+alias symbol "covers" (instance 3) = "new covers set".
 ntheorem new_coverage_infinity:
   ∀A:nAx.∀U:Ω^A.∀a:A. (∃i:𝐈 a. 𝐈𝐦[𝐝 a i] ◃ U) → a ◃ U.
 #A; #U; #a;                                   (** screenshot "n-cov-inf-1". *)