Long code (mathematics)

Math logic
Classification
Type	Block code
Block length	${\displaystyle 2^{n}}$ for some ${\displaystyle n\in \mathbb {N} }$
Message length	${\displaystyle \log n}$
Alphabet size	${\displaystyle 2}$
Notation	${\displaystyle (2^{n},\log n)_{2}}$-code

In theoretical computer science and coding theory, the long code is an error-correcting code that is locally decodable. Long codes have an extremely poor rate, but play a fundamental role in the theory of hardness of approximation.