Infinity symbol 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 Wallis is credited with introducing the infinity symbol with its mathematical meaning in 1655, in his "De sectionibus conicis". Wallis did not explain his choice of this symbol, but it has been conjectured to be a variant form of a Roman numeral for 1,000 (originally CIƆ, also CƆ), which was sometimes
Kronecker symbol Kronecker symbol In number theory, the Kronecker symbol, written as formula_1 or formula_2, is a generalization of the Jacobi symbol to all integers formula_3. It was introduced by . Let formula_3 be a non-zero integer, with prime factorization where formula_6 is a unit (i.e., formula_7), and the formula_8 are primes. Let formula_9 be an integer. The Kronecker symbol formula_10 is defined by For odd formula_8, the number formula_13 is simply the usual Legendre symbol. This leaves the case when formula_14. We define formula_15 by Since it extends the Jacobi symbol, the quantity formula_17 is simply formula_18 when formula_19. When formula_20,