In theoretical chemistry, molecular structure descriptors are used to compute properties of chemical compounds. Among them Wiener, Szeged and detour indices play significant roles in anticipating chemical phenomena. In the present paper, we study these topological indices with respect to their difference number.

abstract let ‎g=(v,e) ‎be a‎ ‎simple ‎connected ‎graph ‎with ‎vertex ‎set ‎v‎‎‎ ‎and ‎edge ‎set ‎‎‎e. ‎the szeged index ‎of ‎‎g is defined by ‎ where ‎ respectively ‎ ‎ is the number of vertices of ‎g ‎closer to ‎u‎ (‎‎respectively v)‎ ‎‎than ‎‎‎v (‎‎respectively u‎).‎ ‎‎if ‎‎‎‎s ‎is a‎ ‎set ‎of ‎size‎ ‎ ‎ ‎let ‎‎v ‎be ‎the ‎set ‎of ‎all ‎subsets ‎of ‎‎s ‎of ‎size ‎3. ‎then ‎we ‎define ‎three ‎...

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.

Zoltan Alexin Department of Informatics University of Szeged [email protected]—szeged.hu Tibor Gyinnithy Research Group on Artifical Intelligence at University of Szeged [email protected]—szeged.hu Csaba Hatvani Department of Informatics University of Szeged [email protected]—szeged.hu LaszlO Tihanyi MorphoLogic Budapest [email protected] Janos Csirik Department of Informatics University of Szeged csiri...

1Department of Biotechnology, University of Szeged, Közép fasor 52, H-6726 Szeged, Hungary; 2Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Temesvári krt. 62, H-6726 Szeged, Hungary; 3Department of Oral Biology and Experimental Dental Research, University of Szeged, Tisza L. krt. 64, H-6720 Szeged, Hungary; 4Institute of Biophysics, Biological Research Cen...

Joseph Molnár1, Yvette Mándi1, Gabriella Spengler1, Ibolya Haszon3, Sándor Turi3, Miklós Kásler4, and Leonard Amaral1,2,* 1Department of Medical Microbiology and Immunobiology, University of Szeged, Szeged, Hungary 2Travel Medicine of the CMDT (Centro de Malaria e Doencas Tropicais), Instituto de Higiene e Medicina Tropical, Universidade Nova de Lisboa, Lisbon, Portugal 3Department of Pediatric...