Versions tested: 0.7b1
Optimal parameters: /m512
Authors: Eugene Shelwien
Algorithms: X86, CM
Notable peformances: -


ASH is basically a rewrite of PPMY

In ash there're more compact tree [compared to PPMY], better weighting function (with automatically tuned parameters), unary coding with SSE for specified number of high-ranked symbols (instead of always mixing whole distributions) - and, now, E8 and better memory overflow handling.

[ASH and PPMY] only have some chances with texts, as there's no sparse contexts or structure handling, and simple bytewise models are generally inferior to bitwise on nonstationary data, as bitwise models adapt faster (8 updates per byte instead of 1).

author's description, email 2009 April 5


The 3 configurations were submitted by the author in April 5, 2009.

(Have info that should be added here? E-mail.)

0.4a fails with Application1: 'Failed to allocate block. :('

0.7 disqualified: crashes when compressing. 0.7b1 refers to the 0.7 executable dated April 17.

Disqualified (why) configurations (with qualification ratings)
Ver Rating CPR DPR S.E. R.E. Ratio C. kB/s D. kB/s
0.7b1 148 139 156 29 93 3.778 139 138
/m512 /w0 /s0 /o6
0.7b1 137 129 145 46 40 3.454 280 280
/m512 /w1 /s1 /o5
0.7b1 134 126 142 47 36 3.431 291 290

Version info

0.7b1, tar: yes, mode: 32-bit, crc32: 432ee93d, decoder: 34 kB, tested: 2010 Apr 19
compression: ash07.exe /q <args> <src> <cfile>
decompression: ash07.exe /q /d <cfile> <src>