kaon, the Knowledge Attribution Ontology by Aidan Hogan and Jodi Schneider (DERI).
orca, the Ontology of Reasoning, Certainty and Attribution, is an ontology for characterizing the certainty of information, how it is known, and its source
I am not sure of the utility of hyperlinks to identify authors when they are not publicly accessible (as is the case here, 9 November 2012).
Being curious about the usage of “orca:directlyLessCertainThan” I searched for its usage, finding only the vocabulary page.
Ditto for: “http://vocab.deri.ie/orca#directlyLessCertainThan.”
Research of usage of terms in ontological vocabularies and the communities that use them, say in the Common Crawl dataset could be quite useful.
Semantics, afterall, are determined by common usage, not decree.