Re: more patents on interval arithmetic implementations

[Arnold Neumaier <Arnold.Neumaier@xxxxxxxxxxxx>]

Dan Zuras Intervals schrieb:
> > Date: Mon, 29 Dec 2008 12:27:34 +0100
> > From: Ulrich Kulisch <Ulrich.Kulisch@xxxxxxxxxxx>
> > > Arnold Neumaier schrieb:
> > >
> > > Several old patents, two by Kulisch, one by Miranker, and one by Rump,
> > > are related to items 2 and 3 (accurate sum and inner product) in
> > > Section 5.1 of the Vienna proposal:
> > >
> > > - Circuitry for generating sums, especially scalar products
> > >   http://www.patentstorm.us/patents/4866653/fulltext.html
> > >
> > > - Circuitry for generating scalar products and sums of floating point
> > >   numbers with maximum accuracy
> > >   http://www.patentstorm.us/patents/4622650/fulltext.html
> > >
> > > - Systolic super summation device
> > >   http://www.patentstorm.us/patents/4751665/fulltext.html
> > >
> > > - Method and circuit arrangement for adding floating point numbers
> > >   http://www.patentstorm.us/patents/4866651/fulltext.html
> > As far as I understand the matter all these patents provide hardware 
> > circuitries to compute sums and dot procducts of  floating-point numbers 
> > exactly. They have been filed more than 20 years ago and thus should all 
> > be expired. 
>
> 	These are relevant to us in that, being expired patents,
> 	the methods described should never be patented again.

How is the life-time of a patent determined?


Arnold Neumaier