Infinity symbol symbol is encoded in Unicode at and in LaTeX as codice_1: formula_4. The Unicode set of symbols also includes several variant forms of the infinity symbol, that are less frequently available in fonts: , and in block Miscellaneous Mathematical Symbols-B. The acid-free paper symbol mentioned above is encoded separately as . Infinity symbol The infinity symbol (sometimes called the lemniscate) is a mathematical symbol representing the concept of infinity. The shape of a sideways figure eight has a long pedigree; for instance, it appears in the cross of Saint Boniface, wrapped around the bars of a Latin cross. However, John
Plane at infinity does make it look "special" in comparison to the other planes of the space. If the affine 3-space is real, formula_2, then the addition of a real projective plane formula_3 at infinity produces the real projective 3-space formula_4. Since any two projective planes in a projective 3-space are equivalent, we can choose a homogeneous coordinate system so that any point on the plane at infinity is represented as ("X":"Y":"Z":0). Any point in the affine 3-space will then be represented as ("X":"Y":"Z":1). The points on the plane at infinity seem to have three degrees of freedom, but homogeneous coordinates are equivalent