OCL25 — Recursivity is not explicitly addressed with examples

Recursivity is not explicitly addressed with examples, although it is mentioned in several places. For example, in p. 16 it is said "The right-hand-side of this definition may refer to the operation being defined (i.e., the definition may be recursive) as long as the recursion is not infinite." I my course I have put the following example (slide 19) A method that obtains the direct and indirect descendants of a person context Person::descendants(): Set body: result = self.children->union( self.children->collect(c | c.descendants()) ) But there is no way to verify whether the above definition, although conceptually correct, is OK with respect to OCL's syntax. Similarly, the same problem arises with recursive association classes, which is covered in Section 7.5.4. I have covered this in my course in slides 29-30 A person is currently married to at most one person context Person inv: self.marriage[wife]>select(m | m.ended = false)>size()=1 and self.marriage[husband]>select(m | m.ended = false)>size()=1 Operation that selects the current spouse of a person context Person::currentSpouse() : Person pre: self.isMarried = true body: if gender = Gender::male self.marriage[wife]>select(m | m.ended = false).wife else self.marriage[husband]>select(m | m.ended = false).husband end However, I suppose that the syntax for the operation currentSpouse is OK with respect to OCL's syntax, although it is not specified explicitly.