Welcome @Yuri_Simione. Stardog natively supprts some of what you're looking for like path with the specialized PATH type queries and clustering through the machine learning features. The other algorithms you mentioned, community detection, PageRank, etc, aren't natively supported but there's no reason that it can't be done. I believe there are some projects out there that try implementing them against a standard sparql endpoint although I can't say what the performance would be. I think there maybe some work going on with the Stardog folks to add those in the futures.
You may also have some success with those using the TinkerPop/Gremlin interface.