diff --git a/.obsidian/app.json b/.obsidian/app.json
index 06f45c7..cf47506 100644
--- a/.obsidian/app.json
+++ b/.obsidian/app.json
@@ -1,7 +1,7 @@
 {
   "promptDelete": false,
   "newLinkFormat": "relative",
-  "attachmentFolderPath": "./assets/引言",
+  "attachmentFolderPath": "./assets/基础概念",
   "showUnsupportedFiles": false,
   "newFileLocation": "current",
   "useMarkdownLinks": true,
diff --git a/.obsidian/workspace.json b/.obsidian/workspace.json
index 3821b78..7f27a54 100644
--- a/.obsidian/workspace.json
+++ b/.obsidian/workspace.json
@@ -13,7 +13,7 @@
             "state": {
               "type": "markdown",
               "state": {
-                "file": "Books/动手学深度学习/引言.md",
+                "file": "Books/动手学深度学习/基础概念.md",
                 "mode": "source",
                 "source": false
               }
@@ -77,7 +77,8 @@
       }
     ],
     "direction": "horizontal",
-    "width": 315.5
+    "width": 315.5,
+    "collapsed": true
   },
   "right": {
     "id": "c501495747cfa761",
@@ -93,7 +94,7 @@
             "state": {
               "type": "backlink",
               "state": {
-                "file": "Books/动手学深度学习/引言.md",
+                "file": "Books/动手学深度学习/基础概念.md",
                 "collapseAll": false,
                 "extraContext": false,
                 "sortOrder": "alphabetical",
@@ -110,7 +111,7 @@
             "state": {
               "type": "outgoing-link",
               "state": {
-                "file": "Books/动手学深度学习/引言.md",
+                "file": "Books/动手学深度学习/基础概念.md",
                 "linksCollapsed": false,
                 "unlinkedCollapsed": true
               }
@@ -133,7 +134,7 @@
             "state": {
               "type": "outline",
               "state": {
-                "file": "Books/动手学深度学习/引言.md"
+                "file": "Books/动手学深度学习/基础概念.md"
               }
             }
           },
@@ -166,9 +167,10 @@
   },
   "active": "82a60b2f86acd8d6",
   "lastOpenFiles": [
+    "Books/动手学深度学习/引言.md",
+    "Books/动手学深度学习/基础概念.md",
     "Books/Java Guide/基础语法.md",
     "Books/Java并发编程/Java并发编程.md",
-    "Books/动手学深度学习/引言.md",
     "Books/从零开始深入学习Spring/IoC.md",
     "Books/Vim实用技巧/一、入门导读.md",
     "Books/从零开始深入学习Spring",
diff --git a/Books/动手学深度学习/基础概念.md b/Books/动手学深度学习/基础概念.md
new file mode 100644
index 0000000..a845d86
--- /dev/null
+++ b/Books/动手学深度学习/基础概念.md
@@ -0,0 +1,12 @@
+# 损失函数
+用来量化预测值与实际值之间的差距。
+一般我们会使用平方误差：
+$l^i(\mathbf{w}, b) = \frac{1}{2}( \hat{y}^i - y^i)$
+损失函数我们则采用平方误差的均值：
+$L(\mathbf{w}, b) = \frac1n\sum_{i=1}^{n} l^i(\mathbf{x}, b)$
+# 优化算法
+- 随机梯度下降算法(Stochastic Gradient Descent)
+  通过不断在损失函数递减方向上更新参数来降低误差。
+  梯度下降法主要计算损失函数关于模型参数的导数。但是每次计算时候遍历整个数据集，效率会很低。所以每次计算先抽取一个小批量$B$(由固定数量的样本组成)的梯度,然后我们将梯度乘以一个预先确定的正数$\eta$，并从当前采纳数的值中减掉。
+  $(\mathbf{w}, b) <- (\mathbf{w},b) - \frac{\eta}{|B|} \sum_{i\in{B}}\partial_{(\mathbf{w}, b)}l^i(\mathbf{w},b)$
+  其中$\eta$代表学习率
diff --git a/Books/动手学深度学习/引言.md b/Books/动手学深度学习/引言.md
index d330b59..8b13789 100644
--- a/Books/动手学深度学习/引言.md
+++ b/Books/动手学深度学习/引言.md
@@ -1,2 +1 @@
-# 关键部分
-## 数据
+