= - \f{\p w^\alf}{\p x_i} .
\ee                 %23

It follows from (20) and (23) that
\begin{equation}
\f {\p u_i}{\p x_k} = \alf_{ik} = \,\stackrel{\circ}{a}_{\alf i}
\f{\p w^\alf}{\p x_k} = \f{\p \stackrel{\circ}{a}_{\alf i} w^\alf}{\p x_k}
\ee                   %24
and therefore the deformation vector ${\bf u}$ and the deformation tensor
$u_{ik}$ in this linear case
are related to their discrete coordinate analogies, $w^\alf$ and
 $\dx \,\stackrel{\circ}{w}_{\alf \beta} = \f{1}{2}\left( \f{\p w_\alf}{\p
N^\beta} + \f {\p w_\beta}{\p N^\alf}\right)$, in the following way:
\begin{equation}
{\bf u} = \,\stackrel{\circ}{\ba}_{\alf} w^\alf, \qquad
u_{ik} = \,\stackrel{\circ}{w}_{\alf \beta} \,\stackrel{\circ}{a}\!{}\!^\alf_i
\,\stackrel{\circ}{a}\!{}\!^{\beta}_k
\ee              %25
where $w_\alf = \,\stackrel{\circ}{g}_{\alf \beta} w^\beta$ are the covariant
components of ${\bf w}$.
\par
In the same way one can obtain the full deformation tensor components [5]:
\begin{equation}
w_{\alf \beta} = \f {1}{2} \left( \,\stackrel{\circ}{\ba}_{\alf} \f {\p{\bf u}}
{\p N^\beta} + \,\stackrel{\circ}{\ba}_{\beta} \f {\p {\bf u}} {\p N^\alf} +
\f {\p {\bf u}} {\p N^\alf} \f {\p {\bf u}} {\p N^\beta} \right)
\ee             %26

\section{ Dynamics and Kinetics of Quasiparticles}
\par
The starting point when deriving Hamilton equations for quasiparticles is that
in the co-moving frame ($C$-system) the dispersion law
$\eps ({\bf k},{g^{\alpha \beta}})$
coincides both with Hamiltonian and with energy. Hence, the equations of
motion in 