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LZW algorithm patent
The LZW algorithm patent, owned and enforced by Unisys, is now expired.
From an archive.org copy of Unisys's LZW page:
Unisys U.S. LZW Patent No. 4,558,302 expired on June 20, 2003, the counterpart patents in the United Kingdom, France, Germany and Italy expired on June 18, 2004, the Japanese counterpart patents expired on June 20, 2004 and the counterpart Canadian patent expired on July 7, 2004.
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