Changes between Initial Version and Version 1 of SigMmt/Templates/RelationOfIndividualsToIndividuals

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Timestamp:
06/05/10 16:39:20 (10 years ago)
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onnopaap (IP: 84.104.92.156)
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  • SigMmt/Templates/RelationOfIndividualsToIndividuals

    v0 v1  
     1=== Base Template !RelationOfIndividualsToIndividuals === 
     2 
     3[[br]]This is a template for expressing that a relation relates individuals only.  
     4[[br]]!RelationOfIndividualsToIndividuals(a) means that a is a relation of one of the subtypes of  
     5!ClassOfRelationship, and that its domain and range (as determined by attributes according  
     6to the entity type) are both first-order classes.  
     7[[br]] 
     8[[br]]Roles:  
     9[[br]]1 hasRelation !ClassOfRelationship  
     10 
     11Axiom:  
     12{{{ 
     13RelationOfIndividualsToIndividuals(x) <->  
     14ClassOfRelationship(x) &  
     15exists y1 exists y2(entityTriple(x, y1, y2) &  
     16ClassOfIndividual(y1) & ClassOfIndividual(y2)) .  
     17}}} 
     18 
     19NOTE The purpose of this unary template is in expressing a constraint on relations. The use of  
     20the disjunctive entityTriple template (annex C.3) in the defining axiom means this template is not  
     21suitable for introducing relations.  
     22 
     23NOTE The template language lacks the expressive power to fully capture the constraint intended  
     24for this template. A full expression would require universal quantification, stating that for every  
     25entity type to which the subject relation belongs, the attributes of the relation are first-order classes.  
     26Universal statements are beyond the scope of template definitions (cf. 5.2, annex H). The template  
     27still captures a useful approximation, because the intended constraint is satisfied given that the the  
     28subject relation has only one pair of attributes (i.e., has unique domain and range). This requirement  
     29is not captured in the ISO 15926-2 or template languages.  
     30 
     31EXAMPLE The expansion of !RelationOfIndividualsToIndividuals(Shaft Seal Connection) is a disjunctive statement that Shaft Seal Connection belongs to one of the subtypes of !ClassOfRelationship, with the appropriate attributes filled by first-order classes. 
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