RDF and RDFS can be saved in a triplestore, then one can extract some knowledge from them using a query language, like SPARQL.
The first version[1][4] was published by the World-Wide Web Consortium (W3C) in April 1998, and the final W3C recommendation was released in February 2014.
RDFS entailment [11]is not very restrictive, i.e. it does not contain a large amount of rules (compared, for example, to OWL) limiting what kind of statements are valid in the graph.
In RDFS 1.1, the domain and range statements do not carry any formal meaning and their interpretation is left up to the implementer.
The example above demonstrated some of the limits and capabilities of RDFS entailment, but did not show an example of a logical inconsistency (which could in layman terms be interpreted as a "validation error"), meaning that the statements the triples make are in conflict and try to express contradictory states of affairs.