Introduction to the Möbius strip: In 1858 AD, German mathematicians Möbius and John Listing discovered that a piece of paper was made by twisting a paper strip 180 degrees and gluing the two ends together. Looped, with magical properties. Ordinary paper tape has two sides (i.e., double-sided curved surface), one front and one back, and the two sides can be painted in different colors; while such paper tape has only one side (i.e., one-sided curved surface), and a small insect can Climb the entire surface without stepping over its edges. This paper strip is called a "Mobius Strip".