Abstract:
In the paper it is shown that when the temperature-conductivity (diffusion coefficient dependence on temperature (concentration) $C$ provides the parabolic operator monotony and besides that vanishes simultaneously with the temperature (concentration) (e. g. $g(c)=Ac^n, 1\leq n<\infty$), then there exists a region for each moment of time, in which the exact solution vanishes, i. e. the heat (substance) propagates with a finite speed.