Recommender systems are intelligent applications that help on-line users to tackle information overload by providing recommendations of relevant items. Collaborative Filtering (CF) is a recommendation technique that exploits users’ explicit feedbacks on items to predict the relevance of items not evaluated yet. In classical CF users’ ratings are not specifying in which contextual conditions the...

We study individual rational, Pareto optimal, and incentive compatible mechanismsfor auctions with heterogeneous items and budget limits. For multi-dimensional valua-tions we show that there can be no deterministic mechanism with these properties fordivisible items. We use this to show that there can also be no randomized mechanismthat achieves this for either divisible or i...

We generalize the classic dynamic single-item search model to multiple items and vector offers for subsets. We first show a computationally feasible way to solve the dynamic optimization problem, and then prove structural results. Although assignment is not generally monotonically increasing in offer value, we show that, in a special case “additive” model, monotonicity holds if costs are submod...

the iranian food consumption program (ifcp), a unique program in iran was developed to aim accurate calculation of nutrient intakes in relation to heart health investigation released in isfahan cardiovascular research center in march 1998 for the first time. the new versions came out along changes in computer technology. this interview-based program is designed to gather data through designed q...

Two-dimensional infrared (2D IR) data are presented for a vibrational probe in three nematogens: 4-cyano-4'-pentylbiphenyl, 4-cyano-4'-octylbiphenyl, and 4-(trans-4-amylcyclohexyl)-benzonitrile. The spectral diffusion time constants in all three liquids in the isotropic phase are proportional to [T*/(T - T*)](1/2), where T* is 0.5-1 K below the isotropic-nematic phase transition temperature (TN...

Objectives: Many aspects of pediatric colonoscopy differ from adult Responses were analyzed and re-sent to the panel for further ratings until consensus was reached. Items that 80% of experts rated as 4 out of 5 were included in the final instrument. Consensus items were compared with those expert consensus regarding items required on a checklist and global rating scale designed to assess the c...