diff --git a/pages/总复习2023t1.md b/pages/总复习2023t1.md
index a2b799f..a01046f 100644
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@@ -1023,6 +1023,7 @@
 						- Durability: :-> The property that ensures committed changes made by a transaction are permanently saved and will survive any subsequent system failures or crashes.
 					- DONE Concurrency control
 						- LATER Meaning of serialisability.
+							- The objective of serialisability is to find nonserial schedules that are equivalent to some serial schedule. Such a schedule is called serialisable.
 						- DONE How locking can ensure serialisability. #flashcard
 							- Locking achieves serializability by using locks to control access to
 							  shared resources (e.g., database objects like tables or rows) and