Linearizable special cases of the QAP
  We consider special cases of the quadratic assignment problem (QAP) that are linearizable in the sense of Bookhold. We provide combinatorial characterizations of the linearizable instances of the weighted feedback arc set QAP, and of the linearizable instances of the traveling salesman QAP. As a by-product, this yields a new well-solvable special case of the weighted feedback arc set problem. 
Eranda Cela and Vladimir G. Deineko and Gerhard J. Woeginger
math.OC cs.DS