commit by user andrea

diff --git a/weblib/tutorial/chapter2.ma b/weblib/tutorial/chapter2.ma
index b81ecb07ce6d173afdb34e42eec39df53b55d412..29979affdfdb0a685fe066f3ce4575eb295aafdf 100644 (file)
--- a/weblib/tutorial/chapter2.ma
+++ b/weblib/tutorial/chapter2.ma
@@ -30,8 +30,8 @@ match n with
 
 (* It is worth to observe that the previous algorithm works by recursion over the first 
 argument. This means that, for instance, (add O x) will reduce to x, as expected, but (add x O)
-is stack. How can we prove that, for a generic x, (add x O) = x? The mathematical tool do it is 
-called induction. The induction principle states that, given a property P(n) over natural 
+is stack. How can we prove that, for a generic x, (add x O) = x? The mathematical tool to do it 
+is called induction. The induction principle states that, given a property P(n) over natural 
 numbers, if we prove P(0) and prove that, for any m, P(m) implies P(S m), than we can conclude
 P(n) for any n.