Mitzenmacher, Michael2016-01-072000Mitzenmacher, Michael. 2000. On the Hardness of Finding Optimal Multiple Preset Dictionaries. Harvard Computer Science Group Technical Report TR-07-00.http://nrs.harvard.edu/urn-3:HUL.InstRepos:24019790Preset dictionaries for Huffman codes are used effectively in fax transmission and JPEG encoding. A natural extension is to allow multiple preset dictionaries instead of just one. We show, however, that finding optimal multiple preset dictionaries for Huffman and LZ77-based compression schemes is NP-hard.en-USResearch Paper or Report2016-01-07