Abraham Lempel has died (the L in LZW compression)

Famed Israeli computer scientist Prof. Abraham Lempel, whose revolutionary work on lossless data compression algorithms served as a precursor of ubiquitous file formats such as MP3 and ZIP, passed away on Sunday at 86. "The Lempel-Ziv algorithm has contributed to the world, free of charge, an unprecedented technology that enables the transfer of data quickly and without loss of data." During his time at HP, the company registered eight patents in his name in the U.S. His historically-important works start with the presentation of the LZ77 algorithm in a paper entitled "A Universal Algorithm for Sequential Data Compression" in the IEEE Transactions on Information Theory, co-authored by Jacob Ziv. The first major milestone of Lempel's oeuvre came in 1977 when he and his colleague Prof. Jacob Ziv published LZ77, the first version of the Lempel-Ziv algorithm, which was followed up the very next year with LZ78. These algorithms and their derivative works formed the basis of several data compression formats that are widely popular to this day, such as TIFF, PNG, ZIP, and GIF, and played a central role in PDF and MP3 formats. The algorithm developed by Lempel and Ziv allows lossless compression, sans prior knowledge of the statistical properties of the data. Many of the compression technologies used today on the Internet in memory devices, computers, and communications were developed based on the algorithm, and the algorithm still influences tech giants and billions of cellphone users. In 2004, the Institute of Electrical and Electronics Engineers named the algorithms a historic milestone in electrical and electronic engineering.