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[helm.git] / helm / software / matita / library / didactic / exercises / natural_deduction1.ma

diff --git a/helm/software/matita/library/didactic/exercises/natural_deduction1.ma b/helm/software/matita/library/didactic/exercises/natural_deduction1.ma
index 8f90dd67c20305403c0dda77b0e63f20b1d9ba2e..c2778fbc5c0b548296f75fd5e0642810558d411e 100644 (file)
--- a/helm/software/matita/library/didactic/exercises/natural_deduction1.ma
+++ b/helm/software/matita/library/didactic/exercises/natural_deduction1.ma
@@ -54,7 +54,7 @@ apply rule (⇒_i [h1] ((G ∧ L ⇒ E) ⇒ F ∧ L ⇒ E));
 apply rule (⇒_i [h2] (F ∧ L ⇒ E));
 apply rule (⇒_i [h3] (E));
 apply rule (∨_e (G∨¬G) [h4] (E) [h4] (E));
-       [ apply rule (lem EM);
+       [ apply rule (lem 0 EM);
        | apply rule (⇒_e (G∧L⇒E) (G∧L));
            [ apply rule (discharge [h2]);
            | apply rule (∧_i (G) (L));
@@ -123,7 +123,7 @@ apply rule (⇒_i [h2] ((¬G ⇒ ¬H) ⇒ H ⇒ E));
 apply rule (⇒_i [h3] (H ⇒ E));
 apply rule (⇒_i [h4] (E));
 apply rule (∨_e (G∨¬G) [h5] (E) [h5] (E));
-       [apply rule (lem EM);
+       [apply rule (lem 0 EM);
        | apply rule (∨_e (E∨F) [h6] (E) [h6] (E));
           [ apply rule (⇒_e (H ⇒ E∨F) (H));
               [ apply rule (discharge [h2]);