I submitted a RAR archive of 645,667 bytes to the Calgary Challenge
) beating the previous best entry of 653,720
bytes. The new entry was created with PAQC, a custom version of PAQ6. For
those interested, PAQC source code can be found at
The previous entry was a SLIM variant by Serge Voskoboynikov in Nov. 2002.
He has improved SLIM by quite a bit since then, so I would not be surprised
if he quickly retakes the lead. However Leo Broukhis has now set a minimum
payout of $100.01 which would require an entry of 634,566 bytes, so it will
take some work.
PAQC is a general purpose archiver although I don't expect the compression
to be quite as good as PAQ6 except on the Calgary corpus. The main
improvements are a better model for pic (about 3K, to 26K), and slightly
better text compression due to removing interference from unneeded models.
However Serge's earlier submission compressed pic to 20K, and current
versions of SLIM are better at text compression than PAQC as well.
My submission was the first under a rule allowing a source code
decompressor. I did not make a big effort to shrink the program. I think
with some work I could probably reduce it from 6K to 3K or better after RAR
-- Matt Mahoney