We propose a new model about diffusion of a product which includes a memory of how many adopters or advertisements a non-adopter met, where (non-)adopters mean people (not) possessing the product. This effect is lacking in the Bass model. As an application, we utilize the model to fit the iPod sales data, and so the better agreement is obtained than the Bass model.

We describe a hierarchical topic model. We assume that there are various levels of specificity in a document collection. For example, a collection of mailing list posts might be organized according to sentence, paragraph, post and thread. We describe a model that captures the structure at each level of the hierarchy. We use a trace norm penalty on a matrix composed of natural parameters for the...

The hierarchical hub covering facility location problems are applied to distribution systems, transportation, waste disposal, treatment services, emergency services and remote communication. The problems attempt to determine the location of service providers' facilities at different levels and specify their linking directions in order to reduce costs and to establish an appropriate condition in...