  Roughly half of numerical investigations of the Anderson transition are based
on consideration of an associated quasi-1D system and postulation of
one-parameter scaling for the minimal Lyapunov exponent. If this algorithm is
taken seriously, it leads to unumbiguous prediction of the 2D phase transition.
The transition is of the Kosterlitz-Thouless type and occurs between
exponential and power law localization (Pichard and Sarma, 1981). This
conclusion does not contradict numerical results if the raw data are
considered. As for interpretation of these data in terms of one-parameter
scaling, such interpretation is inadmissible: the minimal Lyapunov exponent
does not obey any scaling. A scaling relation is valid not for minimal, but for
some effective Lyapunov exponent, whose dependence on parameters is determined
by scaling itself. If finite-size scaling is based on the effective Lyapunov
exponent, existence of the 2D transition becomes not definite, but still rather
probable. Interpretation of the results in terms of the Gell-Mann -- Low
equation is also given.
