generalized BVP; Fredholm mapping
In the paper it is proved that each generalized boundary value problem for the n-th order linear differential equation generates a Fredholm mapping of index zero.
 Hartman, P.: Ordinary differential equations
. John Wiley & Sons, New York-London-Sydney, 1964. MR 0171038
| Zbl 0125.32102
 Šeda, V.: Fredholm mappings and the generalized boundary value problem
. Differential and Integral Equations 8 (1995), 19–40. MR 1296108