Hyper-Wiener Index
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In chemical graph theory, the hyper-Wiener index or hyper-Wiener number is a
topological index In the fields of chemical graph theory, molecular topology, and mathematical chemistry, a topological index, also known as a connectivity index, is a type of a molecular descriptor that is calculated based on the molecular graph of a chemical co ...
of a
molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bioche ...
, used in
biochemistry Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and ...
. The hyper-Wiener index is a generalization introduced by
Milan Randić Milan Randić (born 1 October 1930) is a Croatian American scientist who is one of the leading experts in the field of computational chemistry. Birth and education Randić was born in the city of Belgrade, where his parents, originally from Kostr ...
of the concept of the
Wiener index In chemical graph theory, the Wiener index (also Wiener number) introduced by Harry Wiener, is a topological index of a molecule, defined as the sum of the lengths of the shortest paths between all pairs of vertices in the chemical graph represen ...
, introduced by Harry Wiener. The hyper-Wiener index of a
connected graph In mathematics and computer science, connectivity is one of the basic concepts of graph theory: it asks for the minimum number of elements (nodes or edges) that need to be removed to separate the remaining nodes into two or more isolated subgrap ...
''G'' is defined by : WW(G)=\frac 1 2 \sum_(d(u,v)+d^2(u,v)), where ''d''(''u'',''v'') is the distance between vertex ''u'' and ''v''. Hyper-Wiener index as topological index assigned to ''G'' = (''V'',''E'') is based on the
distance function In mathematics, a metric space is a set together with a notion of ''distance'' between its elements, usually called points. The distance is measured by a function called a metric or distance function. Metric spaces are the most general setting ...
which is invariant under the action of the
automorphism group In mathematics, the automorphism group of an object ''X'' is the group consisting of automorphisms of ''X'' under composition of morphisms. For example, if ''X'' is a finite-dimensional vector space, then the automorphism group of ''X'' is the g ...
of ''G''. Hyper-Wiener index can be used for the representation of
computer networks A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are m ...
and enhancing lattice
hardware security Hardware security as a discipline originated out of cryptographic engineering and involves hardware design, access control, secure multi-party computation, secure key storage, ensuring code authenticity, measures to ensure that the supply chain th ...
. Hyper-Wiener indices used to limit the structure of a particle into a solitary number which signifies the sub-atomic stretching and electronic structures.


Example

One-pentagonal carbon nanocone which is an infinite symmetric graph, consists of one pentagon as its core surrounded by layers of hexagons. If there are ''n'' layers, then the graph of the molecules is denoted by ''G''''n''. we have the following explicit formula for hyper-Wiener index of one-pentagonal carbon nanocone,. : \operatorname(G_n)=20+\fracn+\fracn^2+\fracn^3+\fracn^4+\fracn^5+21n^6


References

{{reflist} Graph invariants