  The problem of quantum state reduction in the process of measurement has
attracted attention of almost everyone who created, developed or explained
quantum physics to the students. Absence of a solution is the basis for the
statement that the physical laws alone are not enough to describe the reduction
of state of the measured particle.
  In the presented study, it is taken into account that the measurement of all
properties of quantum particles can not be carried out in one physical process
(the no-cloning theorem). For such a measurement several series of incompatible
observations are needed, each series is to be carried out by means of a
separate measuring instrument. Each event of measurement is a separate physical
process; combination of different measurement events is performed by the
Measurer - a subject capable of recognizing or not recognizing different events
as similar depending on the purpose of the measurement, and capable as well of
planning the measurements, of obtaining results and making conclusions.
  Several strategies for measuring the quantum state of photon polarization are
considered; it is shown that modeling of a mixed state by a set of photon pure
states is possible only if for this set in all the measurements the same
measuring devices are used. It is also shown that the reduction of the quantum
state is determined by the parameters of interaction of the measuring device
with the measured particle. This fact removes the restrictions on the
magnitudes of correlations of different observables, known as Bell's
inequalities.
