One Problem Pertaining to Servicing of a Flow of Demands by Unreliable Devices

The Mar'yanovich problem [T. P. Mar'yanovich, Ukr. Matem. Zh., 1960, vol. 12, no. 3, pp. 279–286], in which the condition requiring independent restoration of malfunctioning devices is replaced by a more general condition, is solved. Two examples of servicing systems with losses resulting from unreliable devices are also given: the loss probability has the form of the Erlang formula.