Volume 25, No 1, 2018, P.

UDC
K

Abstract:
W

Keywords:

DOI: 10.17377/daio.2018.25.

Y ^1,2
A ²
1. Sobolev Institute of Mathematics,
4 Koptyug Ave., 630090 Novosibirsk, Russia
2. Novosibirsk State University,
2 Pirogov St., 630090 Novosibirsk, Russia
e-mail:

Received
Revised

References