Loyalty is a big part of today's business because retaining a customer is cheaper than attracting a new one. This relationship also holds true in e-commerce. There are many programs on the Internet to enhance loyalty in the electronic environment, most of which can be summarized as frequent...

A tree network is a collection of trees rooted at a common central node. Several types of network design problems can be viewed as requiring the formation of a spanning tree network of minimum length, subject to a bound on the sum of "weights" on the nodes of any component tree. Such problems...