Two different productive digital library projects (say Wikipedia and PM, or the FEM and PM, or PM and one of its mirrors, or AsteroidMeta and one of its mirrors) may have different versions of entries on the same topic. How can these entries, which are leading potentially diverging lives, be kept in synch, or at least how can the content or changes be conveyed to the person or persons who may be interested in them? A system for bi-directional content exchange and updating (a "bidi system") would help automate this process.
The ramifications of such a system are wide. A bi-di updating system would be like an Open Archives OAI-PMH, but for content which is changing and potentially changing in both directions. Not only would it keep harvests from getting "stale", it would allow productive efforts of different communities to leverage each other inasmuch as they overlap. For example, PlanetMath could benefit from improvements to Wikipedia math entries, and vice versa. PlanetMath could benefit from future work on PlanetComputing (CS theory entries are basically math) or PlanetPhysics (the language of physics is math) sites, and vice versa. Even PlanetComputing and PlanetPhysics might want a bi-di exchange, as the theoretical area of the fundamental limits of computing and the implementation of computers are basically physics!
The following are content sharing scenarios in which a bi-di exchange system would be useful.
See below for some comments on differences between some of these scenarios.
The various scenarios described here are somewhat different. The FEM is for the made up primarily of entries from PM with some edits and a few additions, whereas Wikipedia, at present, does not have a whole of content lot in common with PM. Two PM mirrors would have to be kept more or less in synch with one another, but Wikipedia and PM would be expected to diverge. The FEM wants everything coming from PM, but PM certainly doesn't want everything coming from Wikipedia (and presumably Wikipedia doesn't want everything coming from PM). So there are some complexities here.
See the thread "A scholia-based document model," which includes some thoughts on bidi updating, though the sketch given there is quite incomplete.
Putting everything on one computer has a single point of failure. It would be nice to implement techniques for avoiding a single point of failure, creating a WikiFeatures:FailSafeWiki
GNU Arch is useful software for keeping two collections in synch, as well as for maintaining multiply branched projects.
Translated versions of PM are another interesting scenario: I'm not sure whether they are a perfect example of bi-di updating, or a degenerate case, or what. But with translation, the goal is to have something sort of like a mirror, where each entry has been changed quite a bit (textually) - and presumably not changed that much semantically. (Hofstadter has a relatively recent book about semantics and translation out, by the way.) So, anyway, to me it seems that even if translations are not an example of bidi systems, they are very similar, and working on bidi would tend to produce things that would spin off to help with translation (and vice versa). --jcorneli Fri Mar 25 04:45:48 2005 UTC