diff --git a/Concurrent Systems/notes/13 - Weak Bisimilarity.md b/Concurrent Systems/notes/13 - Weak Bisimilarity.md
index b875d53..e58cc45 100644
--- a/Concurrent Systems/notes/13 - Weak Bisimilarity.md	
+++ b/Concurrent Systems/notes/13 - Weak Bisimilarity.md	
@@ -50,4 +50,13 @@ Since Q −τ→ b.0, there must exist a P’ such that P ⇒ P and (P,b.0) ∈
 hence it should be (P,b.0) ∈ S
 
 Contradiction: P can perform a whereas b.0 cannot !!
-Similarly, P/R and Q/R are NOT weakly bisimilar
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+Similarly, P/R and Q/R are NOT weakly bisimilar
+
+### EXAMPLE: Factory
+A factory can handle three kinds of works: easy (E), medium (M), difficult (D).
+
+An activity of the factory consists in receiving in input a work (of any kind) and in producing in output a manifactured work.
+
+The given specification of an activity is the following:
+$$A\triangleq i_{E}.A'+i_{M}. A'+i_{D}.A'$$
+$$A' \triangleq$$
\ No newline at end of file