diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index b39b803..2827bcd 100644
--- a/.obsidian/workspace.json
+++ b/.obsidian/workspace.json
@@ -51,9 +51,9 @@
               "type": "pdf",
               "state": {
                 "file": "Concurrent Systems/slides/class 7.pdf",
-                "page": 5,
+                "page": 8,
                 "left": -23,
-                "top": 149,
+                "top": 103,
                 "zoom": 0.680522565320665
               },
               "icon": "lucide-file-text",
@@ -237,6 +237,7 @@
   "lastOpenFiles": [
     "Concurrent Systems/slides/class 7.pdf",
     "Concurrent Systems/notes/7- MUTEX-free concurrency.md",
+    "Pasted image 20250324092633.png",
     "Pasted image 20250324091452.png",
     "Concurrent Systems/notes/Pasted image 20250324082534.png",
     "Concurrent Systems/notes/6a - Alternatives to Atomicity.md",
@@ -270,7 +271,6 @@
     "HCIW/slides/3Haptic interaction.pdf",
     "HCIW/notes/2 - Interface and Interaction for IoT.md",
     "HCIW/notes/3 - Beacons.md",
-    "Concurrent Systems/notes/images/Pasted image 20250312121828.png",
     "Concurrent Systems/notes/1 - CS Basics2.md",
     "HCIW/notes/1 - UX for IoT.md",
     "HCIW/exercises/Exercise.md",
diff --git a/Concurrent Systems/notes/7- MUTEX-free concurrency.md b/Concurrent Systems/notes/7- MUTEX-free concurrency.md
index 09dd627..9aadb47 100644
--- a/Concurrent Systems/notes/7- MUTEX-free concurrency.md	
+++ b/Concurrent Systems/notes/7- MUTEX-free concurrency.md	
@@ -92,4 +92,12 @@ get_ts(i) :=
 ```
 
 #### Soundness theorem (yes, again)
-this implementation satisfies the three properties of the timestamp generator
\ No newline at end of file
+this implementation satisfies the three properties of the timestamp generator
+1. Validity holds because of property 2.c of the splitter
+2. For consistency, the invocation that terminates increased the value of NEXT before terminating
+	- every process that starts after its termination will find NEXT to a greater value (NEXT never decreases!)
+3. Obstruction freedom is trivial
+
+**REMARK:** this implementation doesn’t satisfy the non-blocking property:![[Pasted image 20250324092633.png]]
+
+### A Wait-free Stack
diff --git a/Pasted image 20250324092633.png b/Pasted image 20250324092633.png
new file mode 100644
index 0000000..afa5075
Binary files /dev/null and b/Pasted image 20250324092633.png differ