Calculate length of path betwen nodes (with unknown edges)?

Question

The problem is how to calculate the distance between two nodes (concepts) in a Triple Store (RDF) using sparql queries without know the type of edges. Essencially, is to use Dij

Answer 1

You can use the same technique that's used in Calculate length of path between nodes?, but you'll need to use a wildcard instead of a particular property. The pattern (<>|!<>) is a wildcard, because every property is either <> or it isn't. You could also use (:|!:), but that will only work if you have a : prefix defined. (<>|!<>) will always work. Here's an example:

@prefix : <urn:ex:>

:a :p :b .
:b :q :c .
:c :r :d .
:d :s :e .

prefix : <urn:ex:>

select ?start ?end (count(?mid) as ?length) {
  ?start (<>|!<>)* ?mid .
  ?mid (<>|!<>)+ ?end .
}
group by ?start ?end

------------------------
| start | end | length |
========================
| :a    | :b  | 1      |
| :a    | :c  | 2      |
| :a    | :d  | 3      |
| :a    | :e  | 4      |
| :b    | :c  | 1      |
| :b    | :d  | 2      |
| :b    | :e  | 3      |
| :c    | :d  | 1      |
| :c    | :e  | 2      |
| :d    | :e  | 1      |
------------------------