  The state space of a polymer molecule is analysed. We show how the size of
the state space can be reduced on the basis of symmetry. In the reduced state
space, the probability of a new state (termed below as class) is equal to the
number of old states represented by the new state multiplied by the probability
of each old state. As an application, the electrophoretic motion of the
molecule in gel is considered. We discuss the influence of the gel medium and
of external field on the molecule states, with absorbing states of hooked
molecules playing a major role. We show that in the case of strong fields both
the velocity and the diffusion coefficient decrease with field. Finally, we
evaluate the time of relaxation to and from the absorbing states. This is done
with a continuous version of the exact enumeration method for weighted
networks.
