Browsing by Author "CANGÜL, İSMAİL NACİ"
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Publication A new method for the sum-edge characteristic polynomials of graphs(Soc Paranaense Matematica, 2022-01-01) Öz, Mert Sinan; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-0700-5774; J-3505-2017In this paper, the determinant of the sum-edge adjacency matrix of any given graph without loops is calculated by means of an algebraic method using spanning elementary subgraphs and also the coefficients of the corresponding sum-edge characteristic polynomial are determined by means of the elementary subgraphs. Also, we provide a formula for calculating the number of smallest odd-sized cycles in a given regular graph.Publication A presentation and some finiteness conditions for a new version of the schiitzenberger product of monoids(Tübitak Bilimsel ve Teknolojik Araştırma Kurumu, 2016-01-01) Karpuz, Eylem Güzel; Ateş, Firat; Cevik, Ahmet Sinan; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-7111-3462; 0000-0002-0700-5774; ABA-6206-2020In this paper we first define a new version of the Schutzenberger product for any two monoids A and B, and then, by defining a generating and relator set, we present some finite and infinite consequences of the main result. In the final part of this paper, we give necessary and sufficient conditions for this new version to be periodic and locally finite.Publication Algebraic structure of graph operations in terms of degree sequences(Etamaths Publ, 2018-01-01) Mishra, Vishnu Narayan; Delen, Sadık; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; J-3505-2017In this paper, by means of the degree sequences (DS) of graphs and some graph theoretical and combinatorial methods, we determine the algebraic structure of the set of simple connected graphs according to two graph operations, namely join and Corona product. We shall conclude that in the case of join product, the set of graphs forms an abelian monoid whereas in the case of Corona product, this set is not even associative, it only satisfies two conditions, closeness and identity element. We also give a result on distributive law related to these two operations.Publication An explicit formula for the harmonic indices and harmonic polynomials of carbon nanocones CNC k (n)(Analytic Publ Co, 2020-01-01) Sardar, Muhammad Shoaib; Xu, Si-Ao; Sajjad, Wasim; Zafar, Sohail; Cangül, İsmail Naci; Farahani, Mohammad R.; CANGÜL, İSMAİL NACİ; 0000-0002-0700-5774; J-3505-2017Let G be a simple molecular graph without directed and multiple edges and without loops. The vertex and edge-sets of G are denoted by V(G) and E(G), respectively. Suppose G is also a connected molecular graph and let u, v is an element of V(G) be two vertices. The harmonic index H(G) of G is defined as the sum of the weights 2(d(u)+d(v))(-1) of all edges in E(G), where d(v) is the degree of a vertex v in G which is defined as the number of vertices of G adjacent to v. The harmonic polynomial of G is defined as H(G, x) = Sigma(e=uv is an element of E(G)) 2x((du+dv-1)) and there is the following nice relation between these two notions H(G) = integral(1)(0) H(G, x)dx. In this paper, we present an explicit formula for the harmonic indices and harmonic polynomials of carbon nanocones CNCk[n].Publication Bounds for the sum of cubes of vertex degrees of splice graphs(Turkic World Mathematical, 2020-01-01) Lokesha, Veerebradiah; Jain, Sushmitha; Muddalapuram, Manjunath; Çevik, Ahmet Sinan; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü.; 0000-0002-0700-5774; ABA-6206-2020; J-3505-2017Some chemically interesting graphs can be derived from simpler graphs by some graph operations. One of the most relevant among these interesting graphs is named as splice graphs. They are related to RNA sequencing and therefore is of great interest. The main target of this paper is to obtain the explicit interpretation of F-index in terms of the graph size and maximum or minimum vertex degrees of special splice graphs.Publication Changing relationship between sets using convolution sums of restricted divisor(Korean Soc Computational & Applied Mathematics-kscam, 2023-01-01) Cangül, İsmail Naci; Kim, Daeyeoul; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; J-3505-2017There are real life situations in our lives where the things are changing continuously or from time to time. It is a very important problem for one whether to continue the existing relationship or to form a new one may change their opinion or position rapidly. In this work, we think of the problem of changing relationships from a mathematical point of view and think of an answer. In some sense, we comment these changes as power changes. Our number theoretical model will be based on this idea. Using the convolution sum of the restricted divisor function E, we obtain the answer to this problem.Publication Computing the hosoya and the merrifield-simmons indices of two special benzenoid systems(Univ Kashan, Fac Mathematical Sciences, 2021-06-01) Öz, Mert Sinan; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; J-3505-2017Gutman et al. gave some relations for computing the Hosoya indices of two special benzenoid systems R-n and P-n. In this paper, we compute the Hosoya index and Merrifield-Simmons index of R-n and P-n, by means of introducing four vectors for each benzenoid system and index. As a result, we compute the Hosoya index and the Merrifield-Simmons index of R-n and P-n, by means of a product of a certain matrix of degree n and a certain vector.Publication Computing the Merrifield-Simmons indices of benzenoid chains and double benzenoid chains(Springer Heidelberg, 2022-10) Öz, Mert Sinan; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-0700-5774; J-3505-2017In this paper, we introduce the Merrifield-Simmons vector defined at a path of corresponding double hexagonal (benzenoid) chain. By utilizing this vector, we present reduction formulae to compute the Merrifield-Simmons index sigma(H) of the corresponding double hexagonal (benzenoid) chain H. As the result, we compute sigma(H) of H by means of a product of some of obtained six matrices and a vector with entries in N. Subsequently, we introduce the simple Merrifield-Simmons vector defined at an edge of given graph G. By using simple Merrifield-Simmons vector we present reduction formulae to compute the sigma(G) where G represents any hexagonal (benzenoid) chain.Publication Computing the number of k-matchings in benzenoid chains(Univ Kragujevac, Fac Science, 2022-01-01) Öz, Mert Sinan; Cangül, Ismail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; 0000-0002-0700-5774; J-3505-2017The Hosoya index is associated with many thermodynamic properties such as boiling point, entropy, total pi-electron energy. Transfer matrix technique is extensively utilized in mathematical chemistry for various enumeration problems. In this paper, we introduce the k-matching vector at a certain edge of graph G. Then by using the k-matching vector and two recurrence formulas, we get reduction formulas to compute k-matching number p(G, k) of any benzenoid chains for for all k >= 0 whose summation gives the Hosoya index of the chain. In conclusion, we compute p(G, k) of any benzenoid chains via an appropriate multiplication of three 4(k+ 1) x4(k+ 1) dimensional transfer matrices and a terminal vector which can be obtained by given two algorithms.Publication Distance eccentric connectivity index of graphs(Kyungpook Natl Univ, Dept Mathematics, 2021-03-01) Alqesmah, Akram; Saleh, Anwar; Rangarajan, R.; Gunes, Aysun Yurttas; Cangul, Ismail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; 0000-0001-6251-5518; 0000-0002-0700-5774; AAG-8470-2021; AGP-4352-2022; J-3505-2017; ACA-0773-2022Let G = (V, E) be a connected graph. The eccentric connectivity index of G is defined by xi(C) (G) = Sigma(u)(is an element of V)((G)) deg(u)e(u), where deg(u) and e(u) denote the degree and eccentricity of the vertex u in G, respectively. In this paper, we introduce a new formulation of xi(C) that will be called the distance eccentric connectivity index of G and defined byxi(De)(G) = Sigma(u is an element of V(G))deg(De)(u)e(u)where deg(De)(u) denotes the distance eccentricity degree of the vertex u in G. The aim of this paper is to introduce and study this new topological index. The values of the eccentric connectivity index is calculated for some fundamental graph classes and also for some graph operations. Some inequalities giving upper and lower bounds for this index are obtained.Publication Edge-zagreb indices of graphs(Turkic World Mathematical Soc, 2020-01-01) Öz, Mert Sinan; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Yamaç, Çilem; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; 0000-0002-0700-5774; ABA-6206-2020; J-3505-2017The algebraic study of graph matrices is an important area of Graph Theory giving information about the chemical and physical properties of the corresponding molecular structure. In this paper, we deal with the edge-Zagreb matrices defined by means of Zagreb indices which are the most frequently used graph indices.Publication Effect of edge and vertex addition on albertson and bell indices(Amer Inst Mathematical Sciences-aims, 2021-01-01) Delen, Sadık; Cangül, İsmail Naci; Delen, Sadık; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü; 0000-0002-0700-5774; J-3505-2017; EUU-3205-2022Topological graph indices have been of great interest in the research of several properties of chemical substances as it is possible to obtain these properties only by using mathematical calculations. The irregularity indices are the ones to determine the degree of irregularity of a graph. Albertson and Bell indices are two of them. Edge and vertex deletion and addition are important and useful methods in calculating several properties of a given graph. In this paper, the effects of adding a new edge or a new vertex to a graph on the Albertson and Bell indices are determined.Publication Encrypting and decrypting algorithms using strong face graph of a tree(Taylor & Francis Ltd, 2020-10-01) Kuppan, R.; Shobana, L.; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; 0000-0002-6401-6533; 0000-0002-0700-5774; ABE-7781-2021; J-3505-2017The encryption and decryption is based upon the type of cryptographic scheme being employed and also in some form of key. It is most closely associated with the development and creation of the mathematical algorithms used to encrypt and decrypt messages. The combination of graph labelling techniques together with cryptography to encrypt and decrypt the numbers has been already an ongoing aspect of research. In this paper, the concept of face antimagic labelling is used for a strong face of duplication of all vertices by the edges of a tree to encrypt and decrypt 13 secret numbers.Publication Entire zagreb indices of graphs(World Scientific Publ Co Pte Ltd, 2018-06-01) Alwardi, Anwar; Alqesmah, Akram; Rangarajan, R.; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Eğitim Fakültesi; 0000-0002-0700-5774; J-3505-2017; ABA-6206-2020The Zagreb indices have been introduced in 1972 to explain some properties of chemical compounds at molecular level mathematically. Since then, the Zagreb indices have been studied extensively due to their ease of calculation and their numerous applications in place of the existing chemical methods which needed more time and increased the costs. Many new kinds of Zagreb indices are recently introduced for several similar reasons. In this paper, we introduce the entire Zagreb indices by adding incidency of edges and vertices to the adjacency of the vertices. Our motivation in doing so was the following fact about molecular graphs: The intermolecular forces do not only exist between the atoms, but also between the atoms and bonds, so one should also take into account the relations (forces) between edges and vertices in addition to the relations between vertices to obtain better approximations to intermolecular forces. Exact values of these indices for some families of graphs are obtained and some important properties of the entire Zagreb indices are established.Publication Harmonic index and zagreb indices of vertex-semitotal graphs(New York Business Global Llc, 2020-01-01) Günes, Aysun Yurttaş; YURTTAŞ GÜNEŞ, AYSUN; Togan, Muge; Demirci, Musa; DEMİRCİ, MUSA; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Anabilim Dalı.; 0000-0001-5349-3978; 0000-0002-0700-5774; A-6557-2018; AAG-8470-2021; J-3505-2017Graph theory is one of the rising areas in mathematics due to its applications in many areas of science. Amongst several study areas in graph theory, spectral graph theory and topological descriptors are in front rows. These descriptors are widely used in QSPR/QSAR studies in mathematical chemistry. Vertex-semitotal graphs are one of the derived graph classes which are useful in calculating several physico-chemical properties of molecular structures by means of molecular graphs modelling the molecules. In this paper, several topological descriptors of vertex-semitotal graphs are calculated. Some new relations on these values are obtained by means of a recently defined graph invariant called omega invariant.Publication Independence number of graphs and line graphs of trees by means of omega invariant(Springer, 2020-02-26) Srivastava, Gautam; Srivastava, Hari Mohan; Ozden, Hacer; ÖZDEN AYNA, HACER; Zihni, Fikriye Ersoy; Erdogan, Fatma Ozen; ÖZEN ERDOĞAN, FATMA; Cangul, Ismail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; 0000-0002-0700-5774; 0000-0002-3991-0488; AAH-5090-2021; ABA-6206-2020; J-3505-2017; AAG-8274-2021A recently defined graph invariant denoted by O(G) for a graph G is shown to have several applications in graph theory. This number gives direct information on the realizability, number of realizations, connectedness, cyclicness, number of components, chords, loops, pendant edges, faces, bridges, etc. In this paper, we use O to give a characterization of connected unicyclic graphs, to calculate the omega invariant and to formalize the number of faces of the line graph of a tree, and give a new algorithm to formalize the independence number of graphs G and line graphs L(G) by means of the support vertices, pendant vertices and isolated vertices in G.Publication Inverse problem for bell index(Univ Nis, Fac Sci Math, 2020-01-01) Togan, Müge; Yurttaş, Aysun; YURTTAŞ GÜNEŞ, AYSUN; Şanlı, Utkum; Çelik, Feriha; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; 0000-0001-5349-3978; 0000-0002-0700-5774; J-3505-2017; AAG-8470-2021Due to their applications in many branches of science, topological graph indices are becoming more popular every day. Especially as one can model chemical molecules by graphs to obtain valuable information about the molecules using solely mathematical calculations on the graph. The inverse problem for topological graph indices is a recent problem proposed by Gutman and is about the existence of a graph having its index value equal to a given non-negative integer. In this paper, the inverse problem for Bell index which is one of the irregularity indices is solved. Also a recently defined graph invariant called omega invariant is used to obtain several properties related to the Bell index.Publication Inverse problem for the forgotten and the hyper zagreb indices of trees(Azarbaijan Shahid Madani Univ, 2022-12-01) Kureethara, Joseph Varghese; Asok, Anjusha; CANGÜL, İSMAİL NACİ; Cangül, İsmail Naci; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Matematik Bölümü.; J-3505-2017Let G = (E(G), V (G)) be a (molecular) graph with vertex set V (G) and edge set E(G). The forgotten Zagreb index and the hyper Zagreb index of G are defined by F(G) = Sigma(u is an element of V) (G) d(u)(3) and HM(G) = Sigma(uv is an element of 2E)(G) (d(u) + d(v))(2) whered(u) and d(v) are the degrees of the vertices u and v in G, respectively. A recent problem called the inverse problem deals with the numerical realizations of topological indices. We see that there exist trees for all even positive integers with F(G) > 88 and with HM(G) > 158. Along with the result, we show that there exist no trees with F(G) < 90 and HM(G) < 160 with some exceptional even positive integers and hence characterize the forgotten Zagreb index and the hyper Zagreb index for trees.Publication Matching number and characteristic polynomial of a graph(Taylor & Francis, 2020-07-11) Yurttaş Güneş, Aysun; Demirci, Musa; Öz, Mert Sinan; Cangül, İsmail Naci; YURTTAŞ GÜNEŞ, AYSUN; DEMİRCİ, MUSA; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü.; 0000-0002-0700-5774; 0000-0002-6439-8439; AAG-8470-2021; A-6557-2018; J-3505-2017Matching number and the spectral properties depending on the characteristic polynomial of a graph obtained by means of the adjacency polynomial has many interesting applications in different areas of science. There are some work giving the relation of these two areas. Here the relations between these two notions are considered and several general results giving this relations are obtained. A result given for only unicyclic graphs is generalized. There are some methods for determining the matching number of a graph in literature. Usually nullity, spanning trees and several graph parts are used to do this. Here, as a new method, the conditions for calculating the matching number of a graph by means of the coefficients of the characteristic polynomial of the graph are determined. Finally some results on the matching number of graphs are obtained.Publication Omega index of line and total graphs(Hindawi, 2021-09-09) Demirci, Musa; Delen, Sadık; Çevik, Ahmet Sinan; Cangül, İsmail Naci; DEMİRCİ, MUSA; Delen, Sadık; CANGÜL, İSMAİL NACİ; Bursa Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Matematik Bölümü.; 0000-0002-6439-8439; 0000-0003-4689-3660; 0000-0002-0700-5774; A-6557-2018; EUU-3205-2022 ; J-3505-2017A derived graph is a graph obtained from a given graph according to some predetermined rules. Two of the most frequently used derived graphs are the line graph and the total graph. Calculating some properties of a derived graph helps to calculate the same properties of the original graph. For this reason, the relations between a graph and its derived graphs are always welcomed. A recently introduced graph index which also acts as a graph invariant called omega is used to obtain such relations for line and total graphs. As an illustrative exercise, omega values and the number of faces of the line and total graphs of some frequently used graph classes are calculated.