Software patents never seemed to be a good idea. At last there is something to substantiate the claim that software should not be patentable. Here is a mathematical proof how US Patent 5,893,120 can be reduced to mathematical formulae, thus making it unpatentable under the US law.
In his other blog entry the author argues that, in fact, any software algorithm can be reduced to mathematical formulae, which are not patentable.
Alluve 