# Logarithmic space-constrained reduction

A **logarithmic space-constrained reduction** (also called **logarithmic reduction** ) is a special form of reduction .

In addition to the requirement that a language can be reduced to another language by means of a function
, it must also be possible to calculate this function in
logarithmic space for a **logarithmic reduction** .

Logarithmic reductions are usually used in complexity theory to prove that a language of complexity class NL is also NL-complete .

The notation is often used here.

Note that transitivity can be shown for this reduction . This is the only way to work with this term.