**Valeri G. Sushko**

## Asymptotic Representations for Solutions of Bisingular Problems

**abstract:**

Boundary value problems for partial differential equations
of elliptic, parabolic and mixed types with small parameters by higher order
derivatives are considered. It is assumed that the solution of the
corresponding degenerate equation has singular points and curves where this
solution is non-smooth. Asymptotic representations of solutions of
non-degenerate problems with respect to small parameters are constructed. %

**Mathematics Subject Classification:**
35J70, 35K65, 35M10.

**Key words and phrases:**
Partial differential equation, differential
equation of elliptic type, differential equation of parabolic type,
differential equation of mixed type, singular perturbation, bisingular
boundary value problem, asymptotic representation.