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...

Recently the vertex Padmakar–Ivan (PI v) index of a graph G was introduced as the sum over all edges e = uv of G of the number of vertices which are not equidistant to the vertices u and v. In this paper the vertex PI index and Szeged index of bridge graphs are determined. Using these formulas, the vertex PI indices and Szeged indices of several graphs are computed.

The vertex Padmakar-Ivan (PIv) index of a graph G was introduced as the sum over all edges e = uv of G of the number of vertices which are not equidistant to the vertices u and v. In this paper we provide an analogue to the results of T. Mansour and M. Schork [The PI index of bridge and chain graphs, MATCH Commun. Math. Comput. Chem. 61 (2009) 723-734]. Two efficient formulas for calculating th...

MARTA FILICKOVA, PhD, Researcher at the Department of Pre-School and Elementary Pedagogy and Psychology, Faculty of Education, University of Presov in Presov, Slovakia; e-mail: marta. [email protected] doc. IVETA KOVALCIKOVA, PhD, Associate Professor at Department of Pre-School and Elementary Pedagogy and Psychology, Faculty of Education, University of Presov in Presov, Slovakia. IVAN ROPOVIK,...

The Padmakar–Ivan index of a graph G is the sum over all edges uv of G of number of edges which are not equidistant from u and v. In this work, an exact expression for the PI index of the Cartesian product of bipartite graphs is computed. Using this formula, the PI indices of C4 nanotubes and nanotori are computed. c © 2007 Elsevier Ltd. All rights reserved.

The Padmakar-Ivan (PI) index of a graph G is the sum over all edges uv of G of the number of edges which are not equidistant from u and v. In this paper, the notion of vertex PI index of a graph is introduced. We apply this notion to compute an exact expression for the PI index of Cartesian product of graphs. This extends a result by Klavzar [On the PI index: PI-partitions and Cartesian product...

The main purpose of this paper is to characterize the continuous images of arcs by their images of the weight ≤ א1. More precisely, we will show that a compact space X is the continuous image of an arc if and only if every continuous image Y = f(X) with w(Y)≤ א1 is a continuous image of an arc.

most extensively analysed fungal sequences. As there are now barcode sequences covering all kingdoms of multicellular life, and taxonomists in museums are working hard to keep the molecular information connected to the traditional repositories and species definitions, barcodes offer the opportunity to expand species identification to situations where skilled taxonomists may not be at hand. “As ...

In Comamonas testosteroni strain BR6020, metabolism of isovanillate (iVan; 3-hydroxy-4-methoxybenzoate), vanillate (Van; 4-hydroxy-3-methoxybenzoate), and veratrate (Ver; 3,4-dimethoxybenzoate) proceeds via protocatechuate (Pca; 3,4-dihydroxybenzoate). A 13.4-kb locus coding for the catabolic enzymes that channel the three substrates to Pca was cloned. O demethylation is mediated by the phthala...