On Tue, Sep 30, 2008 at 8:55 PM, Jussi-Ville Heiskanen cimonavaro@gmail.com wrote:
I am aware that I am dating myself there.
As I recall it, (and my recollection is as ever fallible) there was a claim by some that a compression format was protected. And it was upheld. But the mathematical algorithm wasn't protected, so a totally equivalent format was created (and if I recall improved upon) later, and the original claimants for protection got their butts spanked, even though their claim held.
http://en.wikipedia.org/wiki/Compress
LZW was patented. It was replaced, but not by a mathmatically equivalent alternative, but instead by a superior non-identical alternative. This is why .tar.gz files are common today, but tar.Z files are usually not found.
(Likewise gif -> png, but the story was a bit different since it wasn't realized that GIF had patent problems until very late, and it was possible to make non-infringing GIFs by not applying the compression)
It's true that math is not itself patentable in the US. The way software patents are constructed is by saying: "We claim a computer system (a) consisting of transistors and all the usual computer trappings, which is loaded with software (b), which tranforms the computer into a device for performing computation (c; described in great detail), so that the resulting system a+b+c, is useful for performing task X", and that *is* patentable in the US, the patents usually go on to describe every application that they can think of, as well as the most obvious permutations of a,b, and c.
This does have the effect of source code itself not infringing, but that the infringement begins as soon as the source is combined with a computer that can run it. The distinction is interesting to pedants and lawyers, but the end result is nearly the same as if the algorithm were patented.
There are some cases where someone patents a system using algorithm X and it's possible to find some isomorphic Y which does different computation but gets the same result without infringing on the patent, but LZW was not one of those cases. I get the impression that such examples are fairly uncommon.
On Tue, Sep 30, 2008 at 09:19:05PM -0400, Gregory Maxwell wrote:
It's true that math is not itself patentable in the US. The way software patents are constructed is by saying: "We claim a computer system (a) consisting of transistors and all the usual computer trappings, which is loaded with software (b), which tranforms the computer into a device for performing computation (c; described in great detail), so that the resulting system a+b+c, is useful for performing task X", and that *is* patentable in the US, the patents usually go on to describe every application that they can think of, as well as the most obvious permutations of a,b, and c.
Would the patent still apply if I used a babbage difference engine, or an optical computer?
My question is really: how specific are they in describing a computer?
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