On classification and invariants of second order non-parabolic linear partial differential equations in two variables
On classification and invariants of second order non-parabolic linear partial differential equations in two variables
The paper deals with second order abstract linear partial differential equations (LPDE) over a partial differential field with two commuting differential operators. In terms of usual differential equations the main content can be presented as follows. The classification and invariants problems for second order LPDEs with respect to transformationsx=x(ξ,η),y=y(ξ,η),u=h(x,y)v(ξ,η),where x, …