109. Marek Demia雟ki, Zdzis豉w Golda, Waldemar Puszkarz Dynamics of the Ddimensional FRWcosmological Models within the Superstringgenerated Gravity Model Gen. Rel. Grav., vol. 23, pp. 917939 (1991). [abstract] [journal] 
Abstract: We study the dynamics of the generalized $D$dimensional ($D = 1 + 3 + d$) FriedmanRobertsonWalker (FRW) cosmological models in the framework of an extended gravity theory obtained by adding the GaussBonnet term to the standard EinsteinHilbert action. In our discussion we extensively use methods of dynamical systems. We consider models filled in with a perfect fluid obeying the equation of state $p = (\gamma  1)\rho$ and vacuum but nonflat models. We present a detailed analysis of the ten dimensional model and in particular we study the vacuum case. Several phase portraits show how the evolution of this model depends on the parameter $\gamma$. 
110. Andrzej Woszczyna, Andrzej Ku豉k Cosmological perturbations  extension of Olson's gaugeinvariant method Class. Quantum Grav., vol. 6, p. 1665 (1989). [abstract] [journal] 
Abstract: Olson's approach (1976) to gaugeinvariant perturbation theory is extended to spatially curved universes. A simple method of generating new gaugeindependent quantities is discussed.

111. M. Demianski, Z. A. Golda, M. Heller and M. Szyd這wski KantowskiSachs multidimensional cosmological models and dynamical dimensional reduction Class. Quantum Grav., vol. 5, pp. 733742 (1988). [abstract] [journal] 
Abstract: Einstein's field equations are solved for a multidimensional spacetime $(KS)\times T^m$, where ($KS$) is a fourdimensional KantowskiSachs' spacetime (1966) and $T^m$ is an $m$dimensional torus. Among all possible vacuum solutions there is a large class of spacetimes in which the macroscopic space expands and the microscopic space contracts to a finite volume. The authors also consider a nonvacuum case and they explicitly solve the field equations for the matter satisfying the Zel'dovich equations of state (1987). In nonvacuum models, with matter satisfying an equation of state $\rho = \gamma\rho$. $0\leq \gamma\leq 1$, at a sufficiently late stage of evolution the microspace always expands and the dynamical dimensional reduction does not occur. Models $(KS)\times B(IX)\times S^1\times S^1\times S^1\times S^1$ and $(KS)\times B(IX)\times B(IX)\times S^1$, where $B(IX)$ is the Bianchi type$IX$ space, are also briefly discussed. It is shown that there is no chaotic behaviour in these cases. The same conclusion is also valid when oneloop hightemperature quantum corrections generated by a massless scalar field are taken into account. 
112. Leszek M. Soko這wski, Zdzis豉w A. Golda Instability of KaluzaKlein cosmology Phys. Lett., vol. B195, pp. 349356 (1987). [abstract] [journal] 
Abstract: We show that cosmological solutions in KaluzaKlein theory in more than five dimensions are unstable. This is due to the fact that the extra cosmic scale factors appearing in the metric ansatz act as scalar matter fields in the physical fourdimensional spacetime. These fields have physically unacceptable features: their kinetic energy can be negative and the energy spectrum is unbounded from below. To remove the defects a reinterpretation of the cosmological metric ansatz is necessary. 
113. M. Biesiada, Z. Golda and M. Szyd這wski On some group properties of Newtonian static star structure equations J. Phys. A: Math. Gen., vol. 20, pp. 13131321 (1987). [abstract] [journal] 
Abstract: By using Lie group theory, symmetries of the system of equations describing Newtonian static stars in radiative equilibrium are investigated. It turns out that the most general symmetries are those resulting from quasihomologous transformations. These symmetries enforce a corresponding equation of state. Stromgren's homologous stars are a special case of this, more general, class of solutions. 
114. M. Demia雟ki, Z. Golda, L. M. Soko這wski, M. Szyd這wski, P. Turkowski The grouptheoretical classification of the 11dimensional classical homogeneous KaluzaKlein cosmologies J. Math. Phys. , vol. 28, pp. 171173 (1987). [abstract] [journal] 
Abstract: In the context of the classical KaluzaKlein cosmology the genalized Bianchi models in 11 dimensions are considered. These are spacetimes whose spacelike tendimensional sections are the hypersurfaces of transitivity for a tendimensional isometry group of the total spacetime. Such a spacetime is a trivial principal fiber bundle $P(M,G_7)$, where $M$ is fourdimensional physical spacetime with an isometry group $G_3$ (of a Bianchi type) and $G_7$ is a compact isometry group of the compact isometry group of the compact internal space. The isometry group of $P$ is $G_{10} = G_3 \otimes G_7$, hence all the generalized Bianchi models are classified by enumerating the relevant groups $G_7$. Due to the compactness of $G_7$ the result is astonishingly simple: there are three distinct homogeneous internal spaces in addition to the 11 ordinary Bianchi types for $M$. 