Lempel

Lempel is a surname best known in computer science for its association with the Lempel–Ziv family of lossless data compression algorithms. The algorithms were developed by Abraham Lempel and Jacob Ziv and have influenced many later methods.

LZ77, introduced in 1977, uses a sliding window to replace repeated data with references to preceding data in the stream. This approach makes it effective for a wide range of data types and underpins many practical formats by combining with additional coding stages. LZ78, introduced in 1978, builds a dictionary of phrases as the input is processed, emitting codes that refer to dictionary entries; it is conceptually distinct from LZ77 but shares the same foundational idea of exploiting redundancy.

The Lempel–Ziv algorithms have given rise to numerous derivatives and implementations. LZW (Lempel–Ziv–Welch), developed by Terry Welch in 1984, popularized the approach in software and file formats such as GIF. Modern compression standards often combine LZ-style matching with entropy coding, as in DEFLATE, which merges LZ77 with Huffman coding and is used in ZIP, gzip, and PNG.

Notable individuals bearing the surname include Abraham Lempel, a computer scientist who co-developed the Lempel–Ziv methods with Ziv. The Lempel–Ziv lineage continues to influence contemporary data compression research and practice, with applications spanning multimedia, data storage, and transmission.