Infinity symbol in bookbinding to indicate that a book is printed on acid-free paper and will therefore be long-lasting. In modern mysticism, the infinity symbol has become identified with a variation of the ouroboros, an ancient image of a snake eating its own tail that has also come to symbolize the infinite, and the ouroboros is sometimes drawn in figure-eight form to reflect this identification, rather than in its more traditional circular form. In the works of Vladimir Nabokov, including "The Gift" and "Pale Fire", the figure-eight shape is used symbolically to refer to the Möbius strip and the infinite, for instance
Turned A 19th century by Charles Sanders Peirce as a logical symbol for 'un-American' ("unamerican"). The symbol ∀ has the same shape as a capital turned A, sans-serif. It is used to represent universal quantification in predicate logic. When it appears in a formula together with a predicate variable, they are referred to as a "universal quantifier". In traffic engineering it is used to represent flow, the number of units (vehicles) passing a point in a unit of time. Turned A Turned A (capital: Ɐ, lowercase: ɐ, math symbol ∀) is a symbol based upon the letter A. Lowercase ɐ (in two