the padmakar-ivan (pi) index is a wiener-szeged-like topological index which reflectscertain structural features of organic molecules. the pi index of a graph g is the sum of alledges uv of g of the number of edges which are not equidistant from the vertices u and v. inthis paper we obtain the second and third extremals of catacondensed hexagonal systems withrespect to the pi index.

Szeged, Padmakar-Ivan (PI), and Mostar indices are some of the most investigated distance-based Szeged-like topological indices. On other hand, polynomials related to these were also introduced, for example Szeged polynomial, edgeSzeged PI etc. In this paper, we introduce a concept general polynomial connected strength-weighted graph. It turns out that includes all above mentioned infinitely ma...

the padmakar-ivan (pi) index is a first-generation topological index (ti) based on sums overall edges between numbers of edges closer to one endpoint and numbers of edges closer to theother endpoint. edges at equal distances from the two endpoints are ignored. an analogousdefinition is valid for the wiener index w, with the difference that sums are replaced byproducts. a few other tis are discu...

The Padmakar-Ivan (PI) index is a first-generation topological index (TI) based on sums over all edges between numbers of edges closer to one endpoint and numbers of edges closer to the other endpoint. Edges at equal distances from the two endpoints are ignored. An analogous definition is valid for the Wiener index W, with the difference that sums are replaced by products. A few other TIs are d...

The basic connect of systematic software reuse is simple. Develop systems of components of a reasonable size and reuse them. Then extend the idea of component system beyond code alone to requirements, analysis models, design, and test. All the stages of the software development process are subject to reuse. Developers can save problemsolving effort all along the development chain. They can mini...