From ff8c0d0409478810598d702b8a9cbb7d1ce127c0 Mon Sep 17 00:00:00 2001
From: Marco Realacci <marco@marcorealacci.me>
Date: Mon, 17 Mar 2025 09:24:23 +0100
Subject: [PATCH] vault backup: 2025-03-17 09:24:23

---
 .obsidian/workspace.json         | 42 +++++++++++++++++++++++---------
 Concurrent Systems/notes/4b -.md | 10 ++++++++
 2 files changed, 41 insertions(+), 11 deletions(-)
 create mode 100644 Concurrent Systems/notes/4b -.md

diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index 4ceb652..38384e3 100644
--- a/.obsidian/workspace.json
+++ b/.obsidian/workspace.json
@@ -10,17 +10,37 @@
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+              "title": "4b -"
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+        "type": "tabs",
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@@ -80,7 +100,8 @@
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@@ -197,8 +218,10 @@
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-    "HCIW/slides/4 HUI2016-6-forcefeedback.pdf",
+    "Concurrent Systems/slides/class 4.pdf",
+    "Concurrent Systems/notes/4b -.md",
     "Concurrent Systems/slides/class 5.pdf",
+    "HCIW/slides/4 HUI2016-6-forcefeedback.pdf",
     "HCIW/slides/3b Haptic slides.pdf",
     "HCIW/slides/3Haptic interaction.pdf",
     "HCIW/slides/2 Beacon based interfaces.pdf",
@@ -208,7 +231,6 @@
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     "Concurrent Systems/notes/images/Pasted image 20250312121828.png",
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@@ -223,7 +245,6 @@
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@@ -242,7 +263,6 @@
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     "Biometric Systems/notes/7. Face recognition 3D.md",
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\ No newline at end of file
diff --git a/Concurrent Systems/notes/4b -.md b/Concurrent Systems/notes/4b -.md
new file mode 100644
index 0000000..0ab2d79
--- /dev/null
+++ b/Concurrent Systems/notes/4b -.md	
@@ -0,0 +1,10 @@
+### Monitors
+Semaphores are hard to use in practice because quite low level Monitors provide an easier definition of concurrent objects at the level of Prog. Lang.
+
+It guarantees mutual exclusion.
+
+Inter-process synchronization is done through *conditions*, which are objects that provide the following operations:
+- ***wait*:** the invoking process suspends, enters into the condition's queue, and releases the mutex on the monitor
+- ***signal*:** if no process is in the condition's queue, the nothing happens. Otherwise
+	- it reactivates the first suspended process, suspends the signaling process that however has a priority to re-enter the monitor (*Hoare semantics*)
+	- 
\ No newline at end of file