diff --git "a/docs/\350\256\255\347\273\203\350\220\245\344\275\234\344\270\232\344\273\213\347\273\215.md" "b/docs/\350\256\255\347\273\203\350\220\245\344\275\234\344\270\232\344\273\213\347\273\215.md"
index 5b27825..80b08e5 100644
--- "a/docs/\350\256\255\347\273\203\350\220\245\344\275\234\344\270\232\344\273\213\347\273\215.md"
+++ "b/docs/\350\256\255\347\273\203\350\220\245\344\275\234\344\270\232\344\273\213\347\273\215.md"
@@ -11,6 +11,8 @@
 7. test_nativecpu_concat：依赖作业一、作业五
 8. test_nativecpu_elementwise：依赖作业一、作业六
 9. test_nativecpu_transpose：依赖作业一、作业二
+10. test_matmul：依赖作业六
+11. test_graph：无依赖
 
 # 作业题目
 
@@ -189,7 +191,7 @@ optional<vector<Shape>> ConcatObj::inferShape(const TensorVec &inputs) {
 
 难度：⭐⭐⭐
 
-对应测例：``test_element_wise``,``test_nativecpu_elementwise``
+对应测例：``test_element_wise``,``test_nativecpu_elementwise``,``test_matmul``
 
 需要实现的代码块位置：`src/utils/operator_utils.cc`
 
@@ -220,6 +222,7 @@ optional<vector<Shape>> MatmulObj::inferShape(const TensorVec &inputs)
         // TODO：返回经过 matmul 操作后的 shape
         // REF: https://github.com/onnx/onnx/blob/main/docs/Operators.md#gemm
         // =================================== 作业 ===================================
+        return {{}};
     }
 ````
 
@@ -236,6 +239,9 @@ void GraphObj::optimize()
 {
     // =================================== 作业 ===================================
     // TODO: 设计一个算法来实现指定的图优化规则
+    // 图优化规则如下：
+    // 1. 去除冗余的算子（例如，两个相邻的算子都是 transpose 算子，且做的是相反的操作，可以将其全部删除）
+    // 2. 合并算子（例如，矩阵乘算子中含有属性transA、transB，如果其输入存在transpose，且对最后两个维度做交换，就可以将transpose融入到矩阵乘算子的属性中去）
     // =================================== 作业 ===================================
 }
 ````
\ No newline at end of file
diff --git a/include/core/graph.h b/include/core/graph.h
index bf8ce5c..9326eaf 100644
--- a/include/core/graph.h
+++ b/include/core/graph.h
@@ -37,10 +37,6 @@ namespace infini
                 tensors.erase(it);
         }
 
-        void deleteConnection(Tensor tensor, Operator op);
-        void addConnection(Tensor tensor, Operator op);
-        void replaceConnection(Tensor oldInput, Tensor newInput, Operator op);
-
         const TensorVec &getTensors() const { return tensors; }
         const OpVec &getOperators() const { return ops; }
         Tensor getTensor(int) const;
diff --git a/include/core/op_type.h b/include/core/op_type.h
index f1a5115..db67f33 100644
--- a/include/core/op_type.h
+++ b/include/core/op_type.h
@@ -19,7 +19,6 @@ namespace infini
             Concat,
             Div,
             Mul,
-            Reshape,
             MatMul,
             Relu,
             Sub,
diff --git a/src/core/graph.cc b/src/core/graph.cc
index 6903595..3a90637 100644
--- a/src/core/graph.cc
+++ b/src/core/graph.cc
@@ -102,6 +102,9 @@ namespace infini
     {
         // =================================== 作业 ===================================
         // TODO: 设计一个算法来实现指定的图优化规则
+        // 图优化规则如下：
+        // 1. 去除冗余的算子（例如，两个相邻的算子都是 transpose 算子，且做的是相反的操作，可以将其全部删除）
+        // 2. 合并算子（例如，矩阵乘算子中含有属性transA、transB，如果其输入存在transpose，且对最后两个维度做交换，就可以将transpose融入到矩阵乘算子的属性中去）
         // =================================== 作业 ===================================
     }
 
@@ -175,43 +178,6 @@ namespace infini
         return tensors;
     }
 
-    void GraphObj::deleteConnection(Tensor tensor, Operator op)
-    {
-        // if op is target
-        IT_ASSERT(std::find(tensor->getTargets().begin(),
-                            tensor->getTargets().end(),
-                            op) != tensor->getTargets().end());
-        tensor->removeTarget(op);
-        if (tensor->getSource())
-        {
-            tensor->getSource()->removeSuccessors(op);
-            op->removePredecessors(tensor->getSource());
-        }
-    }
-
-    // add op as a target
-    void GraphObj::addConnection(Tensor tensor, Operator op)
-    {
-        tensor->addTarget(op);
-        if (tensor->getSource())
-        {
-            tensor->getSource()->addSuccessors(op);
-            op->addPredecessors(tensor->getSource());
-        }
-    }
-
-    void GraphObj::replaceConnection(Tensor oldTensor, Tensor newTensor,
-                                     Operator op)
-    {
-        // op is a target of old tensor
-        IT_ASSERT(std::find(oldTensor->getTargets().begin(),
-                            oldTensor->getTargets().end(),
-                            op) != oldTensor->getTargets().end());
-        addConnection(newTensor, op);
-        deleteConnection(oldTensor, op);
-        op->replaceInput(oldTensor, newTensor);
-    }
-
     // tensor's "source" and "target" must be in "ops".
     // tensor has no "source" and no "target" must not exist.
     // "inputs" or "outputs" of operators must be in "tensors"
diff --git a/src/core/op_type.cc b/src/core/op_type.cc
index 7699a90..b2a721a 100644
--- a/src/core/op_type.cc
+++ b/src/core/op_type.cc
@@ -17,7 +17,6 @@ namespace infini
             CASE(Div);
             CASE(Cast);
             CASE(Clip);
-            CASE(Reshape);
             CASE(Relu);
             CASE(Transpose);
             CASE(Concat);
diff --git a/src/operators/matmul.cc b/src/operators/matmul.cc
index 139fffb..0ce94a1 100644
--- a/src/operators/matmul.cc
+++ b/src/operators/matmul.cc
@@ -1,6 +1,4 @@
 #include "operators/matmul.h"
-#include "utils/operator_utils.h"
-#include <numeric>
 
 namespace infini
 {
@@ -29,6 +27,7 @@ namespace infini
         // TODO：返回经过 matmul 操作后的 shape
         // REF: https://github.com/onnx/onnx/blob/main/docs/Operators.md#gemm
         // =================================== 作业 ===================================
+        return {{}};
     }
 
 } // namespace infini
\ No newline at end of file