Database queries expressing user preferences have been found to be crucial for personalized applications. Such preference queries, in particular Pareto preference queries, pose new optimization challenges for efficient evaluation. So far however, all known generic Pareto evaluation algorithms suffer from non-linear worst case runtimes. Here we present the first generic algorithm, called Hexagon...

We provide algorithms that find, in case of existence, indefinite nested sum extensions in which a (creative) telescoping solution can be expressed with minimal nested depth.

A hypothesis is nested within a more general hypothesis when it is a special case of the more general hypothesis. Composite hypotheses consist of more than one component, and in many cases different composite hypotheses can share some but not all of these components and hence are overlapping. In statistics, coherent measures of fit of nested and overlapping composite hypotheses are technically ...

Nested set complexes appear as the combinatorial core of De ConciniProcesi arrangement models. We show that nested set complexes are homotopy equivalent to the order complexes of the underlying meet-semilattices without their minimal elements. For atomic semilattices, we consider the realization of nested set complexes by simplicial fans proposed in [FY], and we strengthen our previous result s...

BACKGROUND Despite its benefits, it is uncommon to apply the nested case-control design in diagnostic research. We aim to show advantages of this design for diagnostic accuracy studies. METHODS We used data from a full cross-sectional diagnostic study comprising a cohort of 1295 consecutive patients who were selected on their suspicion of having deep vein thrombosis (DVT). We draw nested case...

A stratified version of nested case-control sampling which we call "countermatching" is presented. This design uses data available for all cohort members to obtain a sample for collecting additional information in a case-control substudy. Hitherto the only stratified sampling design for such studies has involved matching of controls to cases with respect to confounding variables. However, in so...

background: respiratory virus infections in children are a leading cause of morbidity and mortality worldwide. methods : a total of 897 clinical specimens were collected from february 2007 to january 2008 and transported to the na­tional influenza center. two hundred and two samples belonged to children under the age of six from 897 specimens, de­scribed above, were selected. then they were tes...

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Yan et al. have published a useful paper about thyroid dysfunction (TD) in cases with hepatitis C by treatment with interferon (1). There are some comments which may explicit benefits of this paper in more details. When we report a methodological or statistical issue it is...