Patent on Burrows-Wheel Transform Range Encoding Compression Expired in 2017

Range Encoding, also known as arithmetic encoding, is the practical extension of arithmetic encoding https://www.drdobbs.com/cpp/data-compression-with-arithmetic-encodin/240169251 to arbitrary data sets. https://en.wikipedia.org/wiki/Range_encoding

The most well known range encoding algorithm is probably the one used in 7zip https://en.wikipedia.org/wiki/Lempel%E2%80%93Ziv%E2%80%93Markov_chain_algorithm

however burrows wheel transform based compression appears to improve over Lempel-Ziv. https://en.wikipedia.org/wiki/Burrows%E2%80%93Wheeler_transform

Many of the best performers of the calgary challenge have been Burrows-Wheel transform based algorithms http://mattmahoney.net/dc/dce.html

but it was patent encumbered until 2017. http://www.compressconsult.com/szip/ Michael Schindler's szip with patent https://patents.google.com/patent/US6199064B1/en