The general Friedmann equation: a mathematical point of view
  The note presents a classification of the relevant distinct types of
solutions of the general Friedmann equation without assuming a priori
restrictions for the parameters occurring in this equation. The emphasis is on
the case of a non-vanishing cosmological constant. The classification uses
algebraic criteria. The result is: There are four distinct basic types of
models. Explicit formulas for decisive terms are given. Characteristic mutual
relations of cosmological constant, mass and radiation density to distinguish
between the models are calculated.
