Consider k equal size treatment groups and let the outcome of interest be a survival time. Suppose that a known monotone transformation of the survival times is logistically distributed and that the treatment only affects the location parameter. We obtain exact results for the problem of selecting a subset of treatments, based on the i-th ordered survival times, which contains with specified pr...

This paper explores the problem of feature subset selection for unsupervised learning within the wrapper framework. In particular, we examine feature subset selection wrapped around expectation-maximization (EM) clustering with order identiication (identifying the number of clusters in the data). We investigate two diierent performance criteria for evaluating candidate feature subsets: scatter ...

Let H denote a finite simple hypergraph. The cover ideal of H, denoted by J = J(H), is the monomial ideal whose minimal generators correspond to the minimal vertex covers of H. We give an algebraic method for determining the chromatic number of H, proving that it is equivalent to a monomial ideal membership problem involving powers of J . Furthermore, we study the sets Ass(R/Js) by exploring th...

The paper deals with the reliability–based design optimization (RBDO) of concrete gravity dams subjected to earthquake load using subset simulation. The optimization problem is formulated such that the optimal shape of concrete gravity dam described by a number of variables is found by minimizing the total cost of concrete gravity dam for the given target reliability. In order to achieve this p...

A new way of constructing (minimal) perfect hash functions is described. The technique considerably reduces the overhead associated with resolving buckets in two-level hashing schemes. Evaluating a hash function requires just one multiplication and a few additions apart from primitive bit operations. The number of accesses to memory is two, one of which is to a fixed location. This improves the...

We consider the problem of covering the complete r-uniform hypergraphs on n vertices using complete r-partite graphs. We obtain lower bounds on the size of such a covering. For small values of r our result implies a lower bound of Ω( e r r √ r n log n) on the size of any such covering. This improves the previous bound of Ω(rn log n) due to Snir [5]. We also obtain good lower bounds on the size ...

Since knowledge bases (KBs) are usually incomplete, they should be able to provide information regarding their own incompleteness, which requires them to introspect on what they know and do not know. An important area of research is to devise models of introspective reasoning that take into account resource limitations. Under the view that a KB is completely characterized by the set of beliefs ...