The Similarity Ontology is discussed in When owl:sameAs isn’t the Same: An Analysis of Identity in Linked Data. It defines properties that can be used when you almost mean owl:sameAs.
The properties seem useful. However, it isn't clear how actively maintained or used the ontology is. For example, a link to a supporting ontology defined in the same paper doesn't work. The preferred prefix isn't registered in prefix.cc. And the ontology itself makes assertions that don't match the human-readable comments.
For example, the "matches" property is defined with the following rdf:types
Which I would assume make it symmetric and transitive, but not reflexive. However, the comment says "A is a match to B, they are exactly alike, but may not be one in the same. This property is reflexive and symmetric."
Does anyone know whether this ontology is used in practice and what its maintenance status is?
Another option to see how often some property or class is used is vocab.cc, which I believe indexes content from the Billion Triple Challenge dataset(s). The system is a little broken in that it returns an error instead of no results, and it seems to return an error for many of those properties. I don't believe that the Similarity Ontology has seen much by way of adoption, no.
In any case, the semantics of the properties in that ontology are not very useful and are by no means an alternative for
The only complementary option I see that's needed for
With respect to the paper in question, though it raises an important issue and has interesting discussion/summarisation of the problem, I don't believe that the problem is quite as widespread as their analysis makes out to be. Sure, there's some really bad
I'll take a Web of Data with