On Mon, 5 Jul 2010 23:33:45 -0400, Gerhard Postpischil wrote: >On 7/5/2010 11:12 PM, Rick Fochtman wrote: >> Not inevitable. Souce code usually achieves 60%-90% compression >> with the hard-coded tables in use so far. But the table is >> biased toward source code and doesn't work so well with load >> modules. > The key word is "usually".
>There exists a formal proof that for any compression algorithm, >there will be input resulting in larger output (i.e., you can't >get something for nothing), but I'm too lazy and tired to track >it down now. ... > No need to look anything up. It's a very basic application of the pigeonhole principle. > ... This is one reason why PKZIP, for example, supports >more than one compression method. > And that doesn't help. Just consider PKZIP in its entierty as a complex compression algorithm with several subroutines. The formal proof applies to PKZIP regardless of its internal complexity. -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
