Parabolic equations with a varying direction of time in Holder Spaces and nonclassical differential-operator equations.
Main publications:
I. E. Egorov, S. G. Pyatkov, S. V. Popov, The nonclassical differential-operator equations, Nauka, Novosibirsk, 2000, 336 pp.
S. V. Popov, “About smoothness of solurions of the parabolic equations with a varying direction of evolution”, Reports of Academy of Sciences, 400:1 (2005), 29–31