On various joint measurements of position and momentum observables in quantum theory

In this paper the problem of simultaneous measurability of complementary physical quantities, and the relevance of the uncertainty relations to this question, is analyzed. Formalizing carefully the crucial notations involved in the problem it is shown that the well-known apparently contradictory viewpoints on the subject matter are all true in pointing to a different aspect of one and the same fundamental fact expressed here as complementarity.