That is in no way a normal SPARQL query. I don't know where in particular you got it, but it is an example of Blazegraph/BigData's "GAS" API. It's not an example of idiomatic SPARQL at all.
https://wiki.blazegraph.com/wiki/index.php/RDF_GAS_API That is a specialist extension API for one product's particular capability. You can refer to any number of good tutorials for how to write normal SPARQL. Jena itself maintains one: https://jena.apache.org/tutorials/sparql.html --- A. Soroka The University of Virginia Library > On Mar 5, 2017, at 11:37 AM, Laura Morales <[email protected]> wrote: > >> Could you be more specific about these intuitions and difficulties? > > with other query languages such as gremlin you start from a vertex (or set of > vertices), and follow links (predicates). This is very intuitive, because it > resemble the picture of a graph that I have in mind. For example, I can start > from the vertex "Bruce Springsteen" and follow its out-links > "some_namespace:song". Very easy to understand and work with. SPARQL, at > least to me, seems to be way more intricate, messy, verbose, and ultimately > difficult to understand. Just look at this query (copied from wikidata > examples) for a query as simple as "Children of Genghis Khan".... I barely > understand how to read it to be honest > > #Children of Genghis Khan > #added before 2016-10 > #defaultView:Graph > > PREFIX gas: <http://www.bigdata.com/rdf/gas#> > > SELECT ?item ?itemLabel ?pic ?linkTo > WHERE > { > SERVICE gas:service { > gas:program gas:gasClass "com.bigdata.rdf.graph.analytics.SSSP" ; > gas:in wd:Q720 ; > gas:traversalDirection "Forward" ; > gas:out ?item ; > gas:out1 ?depth ; > gas:maxIterations 4 ; > gas:linkType wdt:P40 . > } > OPTIONAL { ?item wdt:P40 ?linkTo } > OPTIONAL { ?item wdt:P18 ?pic } > SERVICE wikibase:label {bd:serviceParam wikibase:language "en" } > }
