In what sense is AGROVOC a concept scheme? AGROVOC is a concept scheme in the sense that it attempts to provide an organization of the domains related to agriculture. AGROVOC is also a concept scheme in a more technical meaning, related to the fact that AGROVOC consists of a number of SKOS concepts. AGROVOC was born as a purely terminological resource hierarchically organized, i.e., a thesaurus. Now, AGROVOC is a full fledged web oriented resource available in RDF, in which all notions related to thesauri (e.g., the traditional notions of RT and BT/NT) have a translation into SKOS properties.
Concepts and terms - what is the difference? A Concept may be just anything about which we want to say something. Concepts are represented by terms, i.e. words in a given language. In SKOS, concepts are formalized as skos:Concept and identified by dereferenceable Uniform Resource Identifier (URIs), that is, URL. For example, URI http://aims.fao.org/aos/agrovoc/c_12332 is the AGROVOC concept for maize. Terms, or labels, are the actual terms used to name a concept. For example maize, maïs, 玉米, ข้าวโพด are all labels for the same concept in English, French, Chinese, Thai respectively. In AGROVOC, concepts always have at least one preferred term (or descriptor, in the classical terminology of thesauri) in each given language, and zero or more non-preferred terms. In the RDF jargon, terms are called labels: preferred labels, and non preferred labels. In order to achieve more expressivity, AGROVOC uses the SKOS extension for labels, SKOS-XL. The predicates used are: skosxl:prefLabel, used for preferred terms (“descriptors” in thesaurus terminology), and skosxl:altLabel, used for non- preferred terms.
How is AGROVOC organized? AGROVOC is organized as a hierarchy of concepts that have names in various languages. AGROVOC concepts are hierarchically organized under 25 general top concepts, such as: activities, processes, methods etc. Concepts may also be linked by non hierarchical relations, either expressing a generic notion of “relatedness”, or expressing some more refined relation (e.g. something “is a product of” something else). From a formal point of view, AGROVOC is an RDF/SKOS-XL concept scheme. The classical BT/NT thesauri relations are expressed by the SKOS predicates skos:broader and skos:narrower. For non-hierarchical relations between concepts and terms, AGROVOC uses the SKOS property skos:related, and a number of subproperties of skos:related, that are grouped together and called the Agrontology vocabulary.
AGROVOC RDF file. What should I do with it? AGROVOC.rdf is a file containing the AGROVOC data in RDF-SKOS format or rather, various serializations of RDF: RDF/XML, N3, NQ, TRIX. It is not a program to install! The file is big, but usually RDF files are not built to be read by humans, but by machines. Files like that are either loaded into a triple store (e.g., Sesame, OWLIM, ...) or loaded into an rdf editor/viewer (e.g. TopBraid, Protégé) or parsed by an application (by IT people...). Once in your triple store (e.g. OWLIM, Sesame), you can manipulate the data as you like and use it in your application. However, if your goal is simply to look at the AGROVOC content, we suggest that you use either the online AGROVOC browsing tool, or the web-based AGROVOC editing tool.