The previous sections have discussed complementation of nouns by means of noun phrases or PPs. There is only a restricted set of nouns that allow this kind of modification. Three classes were distinguished: (i) relational nouns, which are typically non-derived; (ii) nominalizations derived from verbs or adjectives; and (iii) picture/story nouns, which may be either derived or non-derived. To all these different types of nouns, we have applied the four tests described in Section 2.2.1 for distinguishing adjuncts from complements. On the whole, application of these tests has proved useful in gaining more insight in the status of the PPs accompanying these nouns, not in the least because in many cases the results are unexpected and the discussion provided us with interesting new material for further research. At the same time, the fact that it is often not possible to give a clear-cut answer to the question as to whether a certain constituent functions as an adjunct of as a complement raises the question of how real this distinction is.
      Let us briefly evaluate the results of the tests. The first test concerning the obligatoriness of the PP is always somewhat problematic because the context plays a crucial role in deciding whether a certain element can or cannot be left out. By and large, however, intuitions seem to agree on which element should, in principle, always be present. The second test according to which complement van-PPs can be used as the predicate in a copular construction works quite well, but only distinguishes possessive van-PPs from other van-PPs. The third test concerning R-pronominalization also works quite well, but has the disadvantage of not being readily applicable to +human constituents. The results of the final test concerning PP-extraction are far from unequivocal; only topicalization seems to provide a more or less reliable indication of the status of the element in question.
      As indicated before, the systematic application of these tests has revealed a number of other unexpected facts. First, there is a marked difference between arguments inherited from a verb that take the form of van-PPs (usually NP-themes in the related verbal constructions) and PPs introduced by other prepositions selected by the base verb. Second, it turns out there is large variation between the different types of deverbal nouns. One would expect the behavior of inherited arguments to be the same for all instances of nominalization, regardless of the type of nominalization and the preposition used. Yet, there is a clear difference between, for instance, ing-nominalizations and inf-nominalizations as far as the outcome of the tests is concerned. This seems to indicate that the degree of verbalness of the constructions (the number of verbal features it exhibits) plays a role in the outcome of the tests, as ing-nominalizations are by far the most nominal and inf-nominalizations by far the most verbal of the deverbal nouns. Third, the tests work relatively well for theme arguments, but are not easily applicable to agent or recipient arguments. In particular it turns out that although the agent is an obligatory argument in the verbal domain, agents do not behave as obligatory complements in the nominal domain, even though in most cases the agent is implicitly present. Recipients behave more like themes, but their complement status is nevertheless less obvious.