Compact Inverses of The Multipoint Normal Diferential Operators For   First Order
  In this work, firstly all normal extensions of a multipoint minimal operator generated by linear multipoint diferential-operator expression for first order in the Hilbert space of vector functions in terms of boundary values at the endpoints of the infinitely many separated subintervals are described. Finally, a compactness properties of the inverses of such extensions has been investigated. 
E. Unluyol and E. Otkun Cevik and Z.I. Ismailov
math.FA