letterpair

A letterpair is a sequence of two adjacent letters within a word or text. These pairs are fundamental units in written language and play a role in various linguistic and computational analyses. For instance, in English, common letterpairs include "th," "he," "in," and "er." The frequency of these pairs can vary significantly across different languages and even within different styles of the same language.

The concept of letterpairs is utilized in several fields. In cryptography, analyzing letterpair frequencies can aid in breaking simple substitution ciphers, as certain pairs are more likely to appear together than others. In natural language processing and computational linguistics, letterpairs are often used as features for tasks such as spell checking, text generation, and language identification. They can provide a more nuanced understanding of word structure than individual letters alone.

The study of letterpairs can reveal patterns in spelling and pronunciation. For example, the letterpair "qu" is almost always followed by a vowel in English words, reflecting a common phonetic relationship. While the term primarily refers to two letters, the concept can be extended to trigrams (three letters) and higher-order n-grams, which capture more complex sequential patterns in text. Understanding these basic sequential units is a building block for analyzing and processing written language.