- From: Seth Russell <seth@robustai.net>
- Date: Sat, 04 Jan 2003 06:03:05 -0800
- To: Bob MacGregor <macgregor@ISI.EDU>
- CC: www-rdf-interest@w3.org
Bob MacGregor wrote: > Our experience with Jena has exposed some glaring performance weaknesses > in its implementation of reified statements. We hope that these problems > will be rectified in the upcoming Jena 2.0. However, the issues that > surface will have to be addressed by any triple store implementation. > > In some of our applications the truth of a statement (triple) is relative > instead of absolute, ranked according to a probability or to a degree of > trust. The basic processing loop retrieves all statements that match a > particular pattern, and then sifts through the retrieved statements to > pick out the winner according to some metric. In Jena, a reified > statement may or may not be indexed. If its not, then our processing loop > will not find it. Hence, for our applications ALL statements are indexed. > In API terms, this means that all statements must contained by (added to) > a model, whether or not they are reified, and whether or not they can be > considered to be 'true'. Effectively, this means that the Jena 'bit' that > records which statements have been added to a model is useless. > > So the first lesson is that all statements should be indexed (note: > heavyweight KR systems -- CycL, Epikit, Epilog, SNePS, Loom, PowerLoom -- > already do this). > > Secondly, there should be a 'bit' that API users can use to mark > statements as true or not. However, it really should be 'wider' than a > single 'bit'. Give us enough bits (e.g., make it a resource), and we can > use such an attachment to build our own context mechanisms. I think you're on the something here. But what does "it" in your paragraph above refer to ? Does "it" refer to a Jena Model ? And if so, and we have made ~it~ is a resource, well then ~it~ should have a URI (if only internally), right? But then the problem is you don't have a triple anymore, you got a quad. So why not just cop to it .. we need quads ... not triples. [seeAlso <http://robustai.net/sailor/grammar/Quads.html> <http://robustai.net/mentography/mentography.html>]. Seth Russell
Received on Saturday, 4 January 2003 09:03:39 UTC