diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index 63a11b0..48e294b 100644
--- a/.obsidian/workspace.json
+++ b/.obsidian/workspace.json
@@ -11,16 +11,14 @@
             "id": "802d9ec58484849d",
             "type": "leaf",
             "state": {
-              "type": "pdf",
+              "type": "markdown",
               "state": {
-                "file": "HCIW/slides/Beacon based interfaces.pdf",
-                "page": 6,
-                "left": -20,
-                "top": 762,
-                "zoom": 0.759521484375
+                "file": "HCIW/notes/Exercise.md",
+                "mode": "source",
+                "source": false
               },
-              "icon": "lucide-file-text",
-              "title": "Beacon based interfaces"
+              "icon": "lucide-file",
+              "title": "Exercise"
             }
           }
         ]
@@ -197,8 +195,9 @@
   },
   "active": "802d9ec58484849d",
   "lastOpenFiles": [
-    "HCIW/slides/UX for IoT.pdf",
     "HCIW/slides/Beacon based interfaces.pdf",
+    "HCIW/notes/Exercise.md",
+    "HCIW/slides/UX for IoT.pdf",
     "HCIW/slides/Interface and Interaction for IoT.pdf",
     "HCIW/notes/2 - Interface and Interaction for IoT.md",
     "HCIW/notes",
@@ -241,7 +240,6 @@
     "Biometric Systems/notes/11. Fingerprints.md",
     "Foundation of data science/notes/9 Decision tree.md",
     "Biometric Systems/notes/2. Performance indexes.md",
-    "Biometric Systems/notes/8 Face anti spoofing.md",
     "Senza nome.canvas"
   ]
 }
\ No newline at end of file
diff --git a/HCIW/notes/Exercise.md b/HCIW/notes/Exercise.md
new file mode 100644
index 0000000..b0ab74b
--- /dev/null
+++ b/HCIW/notes/Exercise.md
@@ -0,0 +1,20 @@
+### ShopSense
+useful both for users and shop owners!
+
+#### For users
+- for veeeery big shops, help the user move (geolocation)
+
+- send a notification to a fidelized customer (a customer with the shop app installed) for special offers. Personalized based on the users interests (see part 2)
+
+- help the user find the nearest shop assistant.
+
+#### For shop admins
+Data analysis: we can find, for each user, which are his interests (imagine Ikea with a lot of areas) and analyze the data to send special offers.
+
+Furthermore, we can observe which are the most frequented areas of the shop, the areas on which users spend more time, and the time slots of the day in which the shop is more crowded.
+(For this last part, we don't even require users to have the app installed.)
+
+#### Context
+can be used in any kind of shop, it's very versatile.
+#### Requirements
+we take advantage of user smartphones and use beacons receivers in the shop.