diff --git a/School/Analyse/Periode 2/Week 1.md b/School/Analyse/Periode 2/Week 1.md
index 086a8e1..2f6487f 100644
--- a/School/Analyse/Periode 2/Week 1.md	
+++ b/School/Analyse/Periode 2/Week 1.md	
@@ -75,7 +75,14 @@ Unlike parallelism, concurrency is not always about running faster.
 Useful for:
 - App responsiveness.
 - Processor utilization (hide IO time)
-- Failure isolation
+- Failure isolation (interleaving multiple tasks, a exception on one task will not bring down the rest)
+
+# Abstraction in Concurrency
+Concurrent program consists of a finite set of (sequential) processes.
+
+Processes are written using a finite set of statements.
+
+Execution of concurrent program proceeds by exec