... OCL¹

This work was partially supported by the Bayerische Forschungsstiftung.

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... OCL.²

The only mention of Cartesian product in [RAT97] is when introducing the extended variant of the forAll operation, namely the one with more than one iterator: collection->forAll(e1,e2 | <Boolean-expression-on-e1-and-e2>), which in fact is a forAll on the Cartesian product of the collection with itself. The result of an expression of this form is Boolean.

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... either.³

Notice that in general it cannot be ensured that the projection of a set of instances of a class (i.e. a set of n-tuples) is of a type present in the model, thus an operation returning such a set is not expressible in OCL; cf. discussion above on Cartesian products in OCL.

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... if-then-else⁴

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...

In the specification document [RAT97] of OCL, the if-then-else operation is listed among the Boolean ones, of course just the first argument of an if-then-else operation has to be of type Boolean and its result value is of the (least) supertype of the types of the then-branch and of the else-branch.

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... possibility.⁵

This is also true for the negation given the closed world assumption.

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