The linear programming approach to the absolute value problem is to transform the unrestricted variable by the difference of two nonnegative variables. This transformation creates an unbounded feasible region which may lead to erroneous solution. To avoid this, Kaplan [Kaplan, Seymour. 1971....

We consider a single-product periodic-review inventory system for a retailer who has adopted a dual sourcing strategy to cope with potential supply process interruptions. Orders are placed to a perfectly reliable supplier and/or to a less reliable supplier that offers a better price. The success...