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We can define a triangle among the triple of vertices <math>i</math>, <math>j</math>, and <math>k</math> to be a set with the following three edges: {(i,j), (j,k), (i,k)}.  

We can define a triangle among the triple of vertices <math>i</math>, <math>j</math>, and <math>k</math> to be a set with the following three edges: {(i,j), (j,k), (i,k)}.  

我们可以通过'''<font color="#FF8000">边</font>'''集<math>((i,j),(j,k),(i,k))</math>将由'''<font color="#FF8000">顶点</font>'''<math>i</math>,<math>j</math>和<math>k</math>组成的三元组定义为一个三角形。

我们可以通过'''<font color="#FF8000">边</font>'''集<math>((i,j),(j,k),(i,k))</math>，将由'''<font color="#FF8000">顶点</font>'''<math>i</math>,<math>j</math>和<math>k</math>组成的三元组定义为一个三角形。

We can also define the number of triangles that vertex <math>i</math> is involved in as <math>\delta (i)</math> and, as each triangle is counted three times, we can express the number of triangles in G as <math>\delta (G) = \frac{1}{3} \sum_{i\in V} \ \delta (i)</math>.  

We can also define the number of triangles that vertex <math>i</math> is involved in as <math>\delta (i)</math> and, as each triangle is counted three times, we can express the number of triangles in G as <math>\delta (G) = \frac{1}{3} \sum_{i\in V} \ \delta (i)</math>.