The coset pattern matrix (CPM) is formally defined as an elaborate characterization of the aliasing patterns of a fractional factorial design. The possibility of using CPM to check design isomorphism is investigated. Despite containing much information about effect aliasing, the CPM fails to determine a design uniquely. We report and discuss small nonisomorphic designs that have equivalent cose...

The total version of geometric–arithmetic index of graphs is introduced based on the endvertex degrees of edges of their total graphs. In this paper, beside of computing the total GA index for some graphs, its some properties especially lower and upper bounds are obtained.

The F-index of a graph G is the sum of the cubes of the degrees of the vertices of G. In this paper, explicit expressions for the F-index of different transformation graphs of type Gxyz with x, y, z ∈ {−,+} are obtained. F-index for semitotal point graph and semitotal line graph are also obtained here. MSC (2010): Primary: 05C35; Secondary: 05C07, 05C40

Abstract. A simple step-stress accelerated life testing plan is considered when the failure times in each level of stress are geometrically distributed under Type-I censoring. The problem of choosing the optimal plan is investigated using the asymptotic variance-optimality as well as determinant-optimality and probability-optimality criteria. To illustrate the results of the paper, an example i...

The Narumi-Katayama index of a graph was introduced in 1984 for representing the carbon skeleton of a saturated hydrocarbons and is defined as the product of degrees of all the vertices of the graph. In this paper, we examine the Narumi-Katayama index of different total transformation graphs. MSC (2010): Primary: 05C35; Secondary: 05C07, 05C40

This paper examines issues related to various decision-based analytic approaches to sequential choice of projects, with special motivation from and application in the pharmaceutical industry. In particular, the Pearson index and Gittins index are considered as key strategic decision-making tools for the selection of R&D projects. It presents a proof of optimality of the Pearson index based on t...

We study the problem of keeping in main memory an index for a large PAT array stored in secondary storage. This index is used to minimize the number of accesses to secondary memory, performing the main part of the search in main memory. However, we have a maximum allowed size for this index, and it is not clear which is the optimum between keeping many short keys or few long keys. We rst derive...