Date: Mon, 11 Jun 2001 16:02:22 -0700 (PDT) From: Matt Dillon <dillon@earth.backplane.com> To: Mikulas Patocka <mikulas@artax.karlin.mff.cuni.cz> Cc: Jonathan Lemon <jlemon@flugsvamp.com>, hackers@FreeBSD.ORG Subject: Re: Patented algorithm in FreeBSD Message-ID: <200106112302.f5BN2Mx34109@earth.backplane.com> References: <Pine.LNX.3.96.1010612004932.15006D-100000@artax.karlin.mff.cuni.cz>
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:> So it looks like we have prior art by around 6 years, which would
:> invalidate the patent iff it was the same thing.
:
:Does it mean that the algorithm is free to use by everyone or free to use
:only in freebsd? I would like to implemet these page table back pointers
:too and I'm scared by the patent... I don't know how US patent system
:works.
:
:Mikulas
It is free for use by anyone. You always have to worry about auxilary
claims, though... for example, if there are 20 claims and 10 of them
have prior art, then anyone can use the algorithms that have prior art
but *might* *not* be able to modify them if the modifications match
a claim that does not have prior art. On the whole, however, if the
primary claims in a patent have prior art, the whole patent has a good
chance of being invalidated if the patent holders challenge.
The key thing with patents is that they are meaningless until the
patent holder decides to protect them in court by challenging the
people who are supposedly in violation of the patent. If a patent
holder decides to go after you, it can be costly even if you win.
On the flip side, patent holders have to be careful who they go after
because if they lose, their entire patent goes down the drain. Patent
holders usually go after larger companies that they think might fold
rather then go to court. In this case I would judge that the patent
holder would be utterly stupid to go after anyone in regards to this
particular patent, because the prior art is so obvious. But, then
again, this guy patented something that had prior art for years before
his patent so maybe he's just that stupid :-(
-Matt
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