/// <summary> Tries to get a subset relation that is encoded in the specified rule as a rule (that is, its sub-out is the (proper) sub/superset relation and its sub-in is true (or the other way around). </summary>
private SetRelation TryFindRelationAsRule(SemanticRule rule)
{
Contract.Requires(rule != null);
if (rule.Antecedents.Count != 0)//TODO: consider whether it is required that there are no antecedents
return null;
//if the sub-in is just "true", which is assumed to be the case for trivial subset relationships such as T∈U (or the sub-out is, i.e. next if-statement)
if (((Name)rule.SubIn).Notion == DefaultNotions.True && rule.SubOut is CompositeName) //if it is a composition sub-out
return TryFindRelation((CompositeName)rule.SubOut);
if (((Name)rule.SubOut).Notion == DefaultNotions.True && rule.SubIn is CompositeName) //if it is a composition sub-in
return TryFindRelation((CompositeName)rule.SubIn);
return null;
}
private IEnumerable<SetRelation> FindAntecedentlessCorollaryRelations(SemanticRule rule)
{
if (rule.Antecedents.Count != 0)
return null;
return rule.Corollaries.OfType<CompositeName>().Select(TryFindRelation).Where(NotNull);//Note that this counters the behavior to defining multiple set relations as multiple corollaries
}
/// <summary> Tries to find a (proper) subset relation in the specified rule, where a (proper) superset relation is regarded as an inverted (proper) subset relation. </summary>
public IEnumerable<SetRelation> TryGetSubsetRelation(SemanticRule rule)
{
return FindAntecedentlessCorollaryRelations(rule).ConcatIfNotNull(TryFindRelationAsRule(rule));
}
