What I want to do is to see how two entities are related .. I am using the
shortest path as a measure for relatedness. I don't care about what kind of
relations they had. This why I can't specify certain property.
I wonder how { :x DISTINCT(path) ?y } works? What is the output expected for
this query? Is it the same as getting the shortest path from x to y?
Thanks a lot
Mena
----------------------------------------------------
Mena B. Habib
PhD Student
University of Twente
Faculty of Electrical Engineering, Mathematics and Computer Science.
Database Chair
7500AE Enschede, Netherlands
mail: [email protected]
website: http://wwwhome.ctit.utwente.nl/~badiehm/
Phone: +31 53 489 4549
Fax: +31 53 489 2927
Mobile: +31 68 183 2680
-----Original Message-----
From: Andy Seaborne [mailto:[email protected]] On Behalf Of Andy
Seaborne
Sent: Thursday, March 08, 2012 4:51 PM
To: [email protected]
Subject: Re: Loading model into memory
On 08/03/12 15:03, Chris Dollin wrote:
> Mena said:
>
>> I want to apply the OnTools .FindShortestPath function on Yago.
>> I am using the following code to load the model:
>>
>> Model model = TDBFactory.createModel(FullYagoDirectory);
>>
>> The FindShortestPath function taking too much time to return a result.
>> I wonder if it is possible to load the model into main memory to make
>> it faster or if there is any other way to make FindShortestPath much faster.
>
> Model model = ModelFactory.createDefaultModel().add(
> TDBFactory.createModel(FullYagoDirectory) );
>
> Of course you may then run out of memory if the model is big.
>
> Chris
>
> ("Default" models are in-memory models.)
IIRC YAGO(2) is a bit big. The core is something like 30 million triples and
full 80 million triples, I think.
Bit big for memory unless you have a big server.
Do you need "shortest path" or is just connectivity of entities acceptable?
ARQ now has DISTINCT for paths and executes it (more) efficiently:
{ :x DISTINCT(path) ?y }
in the ARQ language.
(more to come here ... "soon")
If you do want "shortest path", you may need to simplify the problem.
Jena's OntTools shortest path is quite general - can you work with, say, the
path being a fixed property?
If so, maybe extract all the occurrences of that property and make a subgraph,
hopefully smaller.
You may need to look at a graph algorithm like the Floyd-Warshall algorithm
[*] which is space-consuming and O(N^3) in time. Being able to reduce to
something smaller helps with the space consumption.
(OntTool.findShortestPath is a simple breadth first search).
Andy
[*] http://en.wikipedia.org/wiki/Floyd%E2%80%93Warshall_algorithm
Andy
