EN
This paper addresses Czech light verb constructions, partly revising principles of their syntactic structure formation formulated within the Functional Generative Description. It argues that obligatoriness of valency complementations should be reflected in these principles. Namely, the role of optional valency complementations of light verbs played in this process has been analyzed. This analysis has shown that in the cases where light verbs do not provide a sufficient number of valency complementations for the surface expression of semantic participants of predicative nouns, semantic participants of nouns make use of optional verbal complementations; namely ORIGin, LOCative and BENefactor have been attested in the VALLEX lexicon. In such cases, semantic participants can be expressed on the surface, either as optional verbal complementation or as nominal complementation. The distribution of verbal and nominal complementations have been observed in 1,600 light verb constructions extracted from the Czech National Corpus, with the result that the surface expression of these participants through the optional verbal complementations is strongly preferred (88% of verbal complementations and 12% of nominal ones). The semantic analysis has indicated that the optional verbal complementations are overrepresented as they cover broader semantic contexts than the corresponding nominal ones.