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As cosmological parameters we consider parameters which define the present and past structure of the Universe. Principal parameters are: the Hubble constant, which characterises the expansion speed of the Universe; the age and acceleration parameter of the Universe; densities of main constituents of the Universe: baryonic matter, dark matter and dark energy; and parameters, which define the amplitude and shape of the power spectrum of galaxies and matter. Cosmological parameters and descriptive functions can be used to test various scenarios of structure evolution.

The Hubble constant, h, can be estimated by several methods: through the ladder of various distance estimators from star clusters to cepheids in nearby galaxies, through the light curves of medium-distant supernovae, or using several physical methods (gravitational lensing, Sunyaev-Zeldovich-effect). Summaries of recent determinations are given in [41, 47]. A mean value of recent determinations is h = 0.65 ± 0.07.

The baryon density can be determined most accurately from observations of the deuterium, helium and lithium abundances in combination with the nucleosynthesis constrains. The best available result is Omegabh2 = 0.019 ± 0.002 [11].

The total density of matter, Omegatot = Omegam + Omegav, determines the position of the first Doppler peak of the angular spectrum of CMB temperature fluctuations; here Omegam and Omegav are the densities of matter and dark (vacuum) energy, respectively. Recent observations show that the maximum of the first Doppler peak lies at l approx 200 [17, 30]. This indicates that Omegatot approx 1. Since this is the theoretically preferred value, I assume in the following that Omegatot = 1.

There exist a number of methods to estimate the density of matter, Omegam = Omegab + Omegac + Omegan, where Omegab, Omegac, and Omegan are the densities of baryonic matter, cold dark matter (CDM), and hot dark matter (HDM), respectively. The luminosity-distance method, used in the distant supernova project, yields Omegam = 0.28 ± 0.05 [43, 45]. Another method is based on X-ray data on clusters of galaxies, which gives the fraction of gas in clusters, fgas = Omegab / Omegam. If compared to the density of the baryonic matter one gets the estimate of the total density, Omegam = 0.31 ± 0.05(h / 0.65)-1/3 [39]. A third method is based on the geometry of the Universe. Observations show the presence of a dominant scale, l0 = 130 ± 10 h-1 Mpc, in the distribution of high-density regions [8, 21, 20]. A similar phenomenon is observed in the distribution of Lyman-break galaxies [9] at high redshift, z approx 3. We can assume that this scale is primordial and co-moves with the expansion; in other words - it can be used as a standard ruler. The relation between redshift difference and linear comoving separation depends on the density parameter of the Universe; for a closed universe one gets a density estimate Omegam = 0.4 ± 0.1. The same method was applied for the distribution of quasars by Roukema & Mamon [46] with the result

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