The model we introduced has no restrictions on potential relationships to be applied. The model is extensible, and any possible specific relationships can be included. We carried out a preliminary linguistic and conceptual analysis of AGROVOC and found a set of relationships; most of them are well known (but it is important to know that they are needed in the food and agriculture domain), some of them add new nuances. Table 5 lists relationship types found in AGROVOC or otherwise proposed here, and subsections 4.1 - 4.3 give an explanation and examples for some of these relationship types; others appear in examples throughout the paper. This section is not in any way intended as a complete list of relationship types; it merely gives examples to illustrate the additional information and clarity of conceptual structure that can be conveyed through more specific relationships. Much more work, including comparison, is needed to converge on a set of relationships to replace the currently used thesaurus relationships BT, NT, RT, USE and UF in a reengineering of AGROVOC.
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Table 5: Concept relationships: Examples |
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X, Y are concepts Isa X <includesSpecific> Y/Y <isa> X Holonymy/meronymy (the generic whole-part relationship) containsSubstance> Y/Y
<substanceContainedIn> X Further relationship examples (some from (Schmitz-Esser 1999) X <causes> Y/Y <causedBy> X |
4.1.1 X <includesSpecific> Y/Y <isa> X (implies X <inheritsTo> Y/Y <inheritsFrom> X)
This is the standard generic relationship between concepts. It can be used for hierarchical inheritance (but is not the only relationship for this purpose). Hierarchical inheritance is useful within the thesaurus/ontology to streamline the writing and presentation of definitions and scope notes and for inheriting relationships. Examples (all NT in AGROVOC unless stated otherwise):
chemical soil types <includesSpecific> saline soils
bovine spongiform encephalopathy <includesSpecific> spongiform encephalopathy
cells <includesSpecific> blood cells
blood cells <includesSpecific> leukocytes
leukocytes <includesSpecific> lymphocytes
lymphocytes <includesSpecific> T-lymphocytes UF in AGROVOC
There are several relationships that fall under the part-whole umbrella. Some of these can be displayed in a hierarchical format. However, the direction of the hierarchy, and the direction of hierarchical inheritance, is sometimes from part to whole and sometimes from whole to part. All relationships are shown starting from the whole first.
Y is the material or substance of which X is made by nature (<containsSubstance>) or by man (<hasIngredient>). Y loses its identity once it is incorporated into X. There is no implication of an "all and only" relation with respect to the composing substance, where Y is the sole substance making up X; but a subsequent refinement could make this distinction. In AGROVOC, this relationship appears as BT/NT or RT; quite often, it does not appear at all. Some examples are given below:
blood <containsSubstance> blood gases
blood <containsSubstance> blood lipids
blood <containsSubstance> blood proteins
blood <containsSubstance> blood cells (borderline case, see comment in 4.2.4)
All NT in AGROVOC
cocoa beverages <hasIngredient> cocoa powder
RT in AGROVOC
X <yieldsPortion> Y describes a relation between a mass X and a piece Y taken from the mass, for example,
roots <yieldsPortion> cuttings RT in AGROVOC
(Note: the example assumes root cuttings, but AGROVOC refers to any kind of cutting.
This relation is used for objects with spatial extent. It holds when X is an inalienable part of Y, identifiable but not inherently separable. These include body parts and geographical locations.
Asia <spatiallyIncludes> East Asia NT in AGROVOC
Transitivity is also a feature of spatial relations. If X <spatiallyIncludes> Y and Y <spatiallyIncludes> Z, then X <spatiallyIncludes> Z.
Asia <spatiallyIncludes> East Asia
East Asia <spatiallyIncludes> China
® Asia <spatiallyIncludes> China
This relationship holds when X is a part of Y that retains its identity as an object even when built into the whole. In addition, each X must be enumerable or nameable, i.e. not part of a mass. Examples:
plough <hasComponent> ploughshare RT in AGROVOC
woody plant <hasComponent> plant anatomy (i.e. parts of plants) RT in AGROVOC
nucleus <hasComponent> chromosome NT in AGROVOC
There are cases when it is hard to decide when to use <containsSubstance> and when to use <hasComponent>; blood <?> blood cell is such a borderline case. We decided on blood <hasComponent> blood cell because each blood cell is a recognizable and separate entity. But one could equally strongly argue for blood <containsSubstance> blood cell because a blood cell is part of a mass and cannot be distinguished from others within the mass; it has at most a very weak identity as an object.
There are many processes in AGROVOC which could be linked using this relation, for example,
ATP cycle <includesSubprocess> phosporylation RT in AGROVOC
X <hasMember> Y indicates a relation of membership within a collective or group or organization.
Francophone Africa <hasMember> Benin RT in AGROVOC
biotope <hasMember> plant not in AGROVOC
pesticide crops <hasMember> Artemisia absynthium RT in AGROVOC
Note that transitivity is not a characteristic of membership relations.
Examples
overgrazing <causes> desertification RT in AGROVOC
Serpulina hyodysenteriae <causes> swine dysentery
preharvest sprouting <causes> crop losses
This relation expresses the fact that concept X is instrumental to achieve, as a result, concept Y. Example:
plough <instrumentFor> ploughing RT in AGROVOC
The instrument considered may be one applied by a living being (man, animal) or a machine or a system. The sense of the relation points to the result achieved by the use of the instrument.
This is a case where X indicates a process involved in Y. Examples:
soil injection <processFor> fertilization RT in AGROVOC
gonadectomy <processFor> sterilization [of organisms] BT in AGROVOC
fertilization <beneficialFor> crop yield Not found in AGROVOC
Pentosan polysulphate <treatmentFor> bovine spongiform encephalopathy Not in AGROVOC
Found in AGROVOC only indirectly. For example, from:
preharvest sprouting <causes> crop losses
one can conclude
preharvest sprouting <harmfulFor> crop yield
Halophytes <growsIn> saline soils RT in AGROVOC
fertilization <hasProperty> application rate RT in AGROVOC
blood circulation <hasProperty> blood pressure NT in AGROVOC
bovine spongiform encephalopathy <similarTo> Creutzfeld-Jakob syndrome RT in AGROVOC
crop losses <oppositeTo> crop yield Not in AGROVOC
This preliminary analysis shows that AGROVOC contains many relationships that can be made more specific in a reengineering project but that some relationship types are missing so relationships need to be added from scratch. Also it is hardly possible to compile a complete inventory of relationship types. Thus, a generic relationship Related Term should still be kept to express residual relationships; such relationship instances should be accompanied by a note that specifies the meaning or intention of the relationship. This will facilitate a later deduction of new relationship types from these residual relationships.
