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Within the framework of a model Universe with variable space dimension, we study chaotic inflation with the potential $m^2\phi^2/2$, and calculate the dynamical solutions of the inflaton field, variable space dimension, scale factor, and their interdependence during the inflationary epoch. We show that the characteristic of the variability of the space dimension causes the inflationary epoch in the variable space dimension to last longer than the inflationary epoch in the constant space dimension.
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