 The time evolution of fields at each spatial point is well approximated by the homogeneous cosmologies in the Bianchi classification.By separating the time and space derivatives in the Einstein equations, for example, in the way used above for the classification of homogeneous spaces, and then setting the terms containing space derivatives equal to zero, one can define the so-called truncated theory of the system (truncated equations).Then, the BKL conjecture can be made more specific