[OSM-legal-talk] ODbL: How obscure/inaccessible can published algorithms be?

[Matt Amos]

On Sat, Dec 12, 2009 at 12:07 PM, Frederik Ramm <frederik at remote.org> wrote:
> Hi,
>
>    OdbL has this requirement where, if you publish a produced work
> based on a derived database, you also have to publish either
>
> (a) the derived database or
> (b) a "diff" allowing someone to arrive at the derived database if he
> has the original, publicly available database or
> (c) an algorithm that does the same.
>
> Is that correct so far?

you don't have to publish any of these. the language used is that you
have to "offer" these things, which means you don't have to be able to
host these things. for example, sending a DVD through the post is in
compliance with the license.

also, these things have to be "in a machine readable form".

> I guess it would probably permitted to specify a number of PostGIS
> commands that achieve the changes. - Let us assume for a moment that
> applying these PostGIS commands would require a machine with 192 GB of
> RAM and Quad Quadcore processors and still take two weeks to complete,
> putting it out of reach of many users. Would it still be permitted to do
> that?

yes.

> Or, would it be allowable to say: "For simplification, a Douglas-Peucker
> algorithm <link to DP wikipedia entry> is used." (leaving open the exact
> implementation and parametrisation of DP - bear in mind that with some
> algorithms, how they work is easily explained but implementing them in a
> way that runs on standard hardware may be a hard task).

no, i don't believe this would constitute "machine readable form".

> Or, would it be allowed to say: "For simplification, just load the data
> set into <name of horribly expensive proprietary ESRI program> and hit
> Ctrl-S X Y, then choose Export to PostGIS"?

i think this would constitute "technological measures" of restriction,
so i think you'd need to provide a parallel distribution of the full
unrestricted output.

> What about: "For simplification, we did the following steps: <detailed
> instructions that are easy to follow>. These steps in this sequence are
> patented by us, so if you want to follow them, please apply to us for a
> license to use our patent."

again, i think this would constitute "technological measures", and
would require a parallel unrestricted distribution.

cheers,

matt