"Nine Chapters of Arithmetic and Business": "If you solve the cube obliquely, you will get two obstacles. The circuitous tunnels are Ma Yang and Turtle Tunnel. It is not easy for a horse to come second and a turtle to come first. Combine two turtles and three into one, and test it with chess, and its shape is revealed. "

Yang Ma, also known as Jiao Liang.

Part of the ancient architecture in China. Used in the 45-degree line between the corner of Si 'a (Huandian) and the corner of Xialiangtou (Xieshan), and installed at the intersection of the two sides of the rafters.

Corner beams only appeared in the past when wood was used as a beam. Now the cities are all concrete, and there are no corner beams. Looking at those scenic spots, it seems that only the ancient buildings of Wang Teng Pavilion exist.