Alphabet

Related Concepts

Encryption; Symmetric Cryptosystem

Definition

An alphabet is a set of characters (literals, figures, and other symbols) together with a strict ordering (denoted by < ) of this set. For good reasons, it is usually required that a set of alphabetic characters has at least two elements and that it is finite. An alphabet Z of n elements is denoted by Z _n , the order is usually the one of the listing.

Background

Z ₂₆ = {a,b,c, …, x,y,z} is the common alphabet of Latin letters of present days. In former times and cultures, the Latin letter alphabet was smaller, so

• Z ₂₁ = Z ₂₆ ∖ {j, k, w, x, y} in Italian until about 1925

• Z ₂₄ = Z ₂₆ ∖ {k, w} in Spanish until about 1950

• Z ₂₅ = Z ₂₆ ∖ {w} in French and Swedish until about 1900

In the Middle Ages, following the Latin tradition, 20 letters seem to have been enough for most writers (with v used for u),

$${Z}_{20} = {Z}_{26}\setminus \{\mathrm{j},\mathrm{k},\mathrm{u},\mathrm{w},\mathrm{x},\mathrm{y}\}.$$

Sometimes, mutated...