of structures. Here, by assumption, the domain ${{\cal D}}$ must remain simply–connected. It is possible to cure this small–scale problem by generalizing the matter model; for example, if multi–streaming is accounted for, an extra term related to velocity dispersion would add up to the kinematical backreaction term. Such a term can regularize singularities as was discussed in detail within the Newtonian framework in [@adhesive].

Derived quantities
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For later convenience we introduce a set of dimensionless average characteristics in terms of which we shall express the solutions: $$\label{omega}
\fl\qquad
\Omega_m^{{{\cal D}}} : = \frac{8\pi G}{3 H_{{{\cal D}}}^2} \langle\varrho\rangle_{\cal D}  \;\;;\;\;
\Omega_{\Lambda}^{{{\cal D}}} := \frac{\Lambda}{3 H_{{{\cal D}}}^2 }\;\;;\;\;
\Omega_{\cal R}^{{{\cal D}}} := - \frac{{\left\langle \cal R \right\rangle_{{\cal D}}}}{6 H_{{{\cal D}}}^2 }\;\;;\;\;
\Omega_{\cal Q}^{{{\cal D}}} := - \frac{{\cal Q}_{{{\cal D}}}}{6 H_{{{\cal D}}}^2 } \;\;.$$ We shall, henceforth, call these characteristics ‘parameters’, but the reader should keep in mind that these are functionals on ${{\cal D}}$. Expressed through these parameters the averaged Hamiltonian constraint (\[averagehamilton\]) assumes the form of a ‘cosmic quartet’: $$\label{hamiltonomega}
\Omega_m^{{{\cal D}}}\;+\;\Omega_{\Lambda}^{{{\cal D}}}\;+\;\Omega_{\cal R}^{{{\cal D}}}\;+\;
\Omega_{\cal Q}^{{{\cal D}}}\;=\;1\;\;.$$ In this set, the averaged scalar curvature parameter and the kinematical backreaction parameter are directly expressed through ${\left\langle \cal R \right\rangle_{{\cal D}}}$ 