From 151e0612f018886acbad8f4f0ff3e6ca1dfa4df8 Mon Sep 17 00:00:00 2001
From: Marco Realacci <marco@marcorealacci.me>
Date: Mon, 24 Mar 2025 08:34:23 +0100
Subject: [PATCH] vault backup: 2025-03-24 08:34:22

---
 .obsidian/workspace.json                               |  8 ++++----
 .../notes/6a - Alternatives to Atomicity.md            | 10 +++++++++-
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index 7d29eb4..75524a4 100644
--- a/.obsidian/workspace.json
+++ b/.obsidian/workspace.json
@@ -6,7 +6,7 @@
       {
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         "type": "tabs",
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+        "dimension": 41.54727793696274,
         "children": [
           {
             "id": "105f7a61963f10e7",
@@ -38,7 +38,7 @@
                 "file": "Concurrent Systems/slides/class 6.pdf",
                 "page": 8,
                 "left": -23,
-                "top": 483,
+                "top": 568,
                 "zoom": 0.6805225653206651
               },
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@@ -218,10 +218,10 @@
       "companion:Toggle completion": false
     }
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-  "active": "105f7a61963f10e7",
+  "active": "6c846cff8fe1d071",
   "lastOpenFiles": [
-    "Concurrent Systems/slides/class 6.pdf",
     "Concurrent Systems/notes/6a - Alternatives to Atomicity.md",
+    "Concurrent Systems/slides/class 6.pdf",
     "Pasted image 20250324082545.png",
     "Pasted image 20250324082534.png",
     "Concurrent Systems/notes/6 - Atomicity.md",
diff --git a/Concurrent Systems/notes/6a - Alternatives to Atomicity.md b/Concurrent Systems/notes/6a - Alternatives to Atomicity.md
index efb046c..68ddf85 100644
--- a/Concurrent Systems/notes/6a - Alternatives to Atomicity.md	
+++ b/Concurrent Systems/notes/6a - Alternatives to Atomicity.md	
@@ -5,4 +5,12 @@ Let us define $op ->_{proc} op'$ to hold whenever there exists a process p that
 
 ![[Pasted image 20250324082545.png]]
 
-The problem with sequential consistency is that it
\ No newline at end of file
+>[!warning]
+>The problem with sequential consistency is that it is NOT compositional.
+
+Consider for example the following two processes:
+```
+p1: Q.enq(a); Q'.enq(b'); Q'deq()->b'
+p2: Q'.enq(a'); Q.enq(b); Q.deq()->b
+```
+