The COOC Criterion (Criterion
of Observations versus
Calculations)

In order to compare the number of different evolutionary stages obtained
and X-ray luminosity of the chosen X-ray sources with the observed galactic
values we use the sum of C/O+O/C, where
C and O are
the calculated and observed values of a given binary type, respectively.
If we make comparison for a number of different binary species (for example,
we compare the number of CV, number of X-ray pulsars,
total X-ray luminosity of LMXB, etc.), we write this criterion in the form:

where the sum is taken for each i-th species, and
are corresponding weights.

Obviously, this function reaches a minimum value of 2 once C=O
for all species. When
at least for one of the species considered, this criterion rapidly increases
(note that always
by definition). This criterion is of course a rough measure of coincidence,
and is used just to somehow compare the values which we know to within
at least a factor of 2. We also note that the criterion in this form accounts,
with equal power, for both rare encountered stages (for example, short-living
superaccreting SS433-like binaries) and copious stages (for example, CV)
of binary evolution.

As was noted by I.E. Panchenko,
, that is our criterion essentially represents a modification of the widely
used
value.