Analyzing pathway energy and time complexity in flower families through vertex-disjoint paths

Jerlinkasmir R1, Veninstine Vivik J.1
1Department of Mathematics, Karunya Institute of Technology and Sciences, Coimbatore-641 114, Tamil Nadu, India.

Abstract

This research delves into the pathway energy framework for flower families, a class of simple connected graphs, whose path matrix P is constructed such that each entry Pij quantifies the maximum number of vertex-disjoint paths. By analyzing the characteristic values of this matrix, we establish the pathway energy bounds specific to these flower graph families. Additionally, a comprehensive algorithm is developed to evaluate the time complexity across different flower family configurations, utilizing numerous trials to capture their average, maximum, and minimum computational behaviors. This analysis offers a comparative study of the structural intricacies that lead to increased computational complexity, highlighting which graph topologies tend to impose higher algorithmic challenges. The proposed method introduces a refined and adaptable approach, deepening the exploration of characteristic graph properties and their computational impact, thereby expanding the practical applications of these findings in graph theory.

Keywords: Characteristics values, Flower families, Energy, Pathway Energy, Time complexity

1. Introduction

Consider an undirected graph G(V,E), where V represents the set of vertices and E denotes the set of edges [5]. The concept of graph energy, first introduced by Ivan Gutman [10,23] in 1978, emerged as a refined extension of the Hückel Molecular Orbital (HMO) theory, originally formulated to quantify the total π-electron energy in molecular systems.

Following this, the concept of graph energy resurfaced as a significant and highly researched theme within chemical graph theory [23], leading to a surge in academic attention, with more than a hundred research papers published annually [11,12]. Numerous properties and well-established bounds associated with graph energy have since been developed and explored extensively [2,3,6].A molecular graph G with n vertices. The eigenvalues of the (0,1)-adjacency matrix of G, denoted by λ1,λ2,,λn, constitute the spectrum of G. The total sum of the absolute values of the eigenvalues of A(G) defines the energy of the graph G [10,24].

In this framework, Patekar et al. introduced a novel concept called the pathway matrix [17,20], which leads to the definition of path energy for a graph, extending the classical notion of graph energy. Define a matrix P=(pij) of dimension n×n, where for ij, pij represents the greatest number of vertex-disjoint paths from vertex vi to vertex vj. For the case where i=j, set pij=0. In the paper by Sabeen et al. [19], the author explores the P(k) pathway energy across various graph classes, deriving key conclusions about the behavior of P(k) path energy. Similarly, Raza et al. [18] in 2023 dig into the spectrum of graphs. In a related study, Xu and Zhou [22] identify the graphs that attain both upper and lower bounds on the path index for graphs with specified structural parameters. In the book by Cvetkovski et al. [7], the authors examine a variety of inequalities, some of which serves as key instruments in tightening the bounds and enhancing the precision of energy calculations within graph structures. We utilize these tools to derive improved upper and lower bounds on the pathway energy for graphs with suitable parameters. Hutter et al. [13] explored the use of machine learning to predict algorithm runtime based on problem-specific features. A simulation of graphs for reduced order modelling in city-scale district energy grids, leveraging spectral graph theory, was recently proposed by Simonsson et al. [21]. Duraj and Mezic [9,15] introduced a novel complexity measure for directed graphs, termed spectral complexity. The spectrum of the path matrix, can be optimally resolved in polynomial time, despite the inherent complexity of the graphs.

2. Motivation and methodology

Graph theory is fundamental in optimizing complex networks, yet calculating pathway energy, key to measuring network connectivity through vertex-disjoint paths-poses significant challenges. Efficient computation of pathway energy is critical for designing robust and high-performing networks. To address the complexity of calculating pathway energy for intricate flower families, we propose a novel algorithmic approach.

Our method constructs a matrix P that represents the maximum number of non-overlapping paths between distinct vertex pairs. From the characteristic values of P, we derive pathway energy bounds, including upper, lower, improved upper, improved lower, and exact limits. We further develop an algorithm that performs n-trial analyses to assess the time complexity of these graphs, by determining average, maximum, and minimum execution times. This approach not only reveals computational challenges across various graph configurations but also provides a streamlined algorithmic framework. By combining advanced mathematical techniques with innovative algorithms, our study offers new insights into network complexity, significantly enhancing both theoretical understanding and practical applications in graph theory.

3. Preliminaries

In this section, the ideas and inequalities that provide the foundation for our work were discussed.

Definition 3.1. (Wheel) [16] A wheel graph Wn is build by connecting each vertex of a cycle Cn to a single hub vertex. This hub is referred to as the central vertex, and the cycle Cn is termed the rim of Wn.

Definition 3.2. (Helm) [16] A helm graph Hn is a graph constructed by linking a pendant edge to every vertex on the outer cycle Cn of a wheel graph Wn.

Definition 3.3. (Flower) [16] A flower graph is generated by connecting a helm graph Hn’s pendent vertices to its center vertex, denoted as Fn.

Definition 3.4. (Sunflower graph) [8] A sunflower graph SFn is constructed by transforming each edge of the circumference of a wheel graph Wn into a triangle. Two triangles are connected by a common vertex if and only if their corresponding edges are adjacent.

Definition 3.5. (Closed Sunflower graph) [4] When independent vertices of a sun flower graph SFn that are not contiguous to its center vertex are joined, a closed sun flower graph CSFn is created, which causes a cycle to occur on n vertices.

Definition 3.6. (Blossom graph) [16] When all the vertices of a closed sun flower graph CSFn are joined to its center vertex, the resulting graph is called a blossom graph Bln.

Theorem 3.7. (Cauchy-Schwarz inequality) [1,7,14] If a1,,an and b1,,bn are real numbers, we have

(1)(i=1naibi)2(i=1nai2)(i=1nbi2).

Theorem 3.8. (Arithmetic and Geometric mean inequality(AM-GM))[1,7,14] Let n be a number of vertex and λi and λj be the characteristic values. (2)1n(n1)ij|λi||λj|(ij|λi||λj|)1n(n1).

Theorem 3.9. (Chebyshev’s Inequality (monotonic Condition)) [7] If {xi} and {yi} are non-decreasing, then: (3)i=1ijnxiyj2n(n1)(i=1nxi)(i=1nyi), with the monotonicity condition from Chebyshev’s Inequality.

Theorem 3.10. (Weighted AM–GM inequality) [7] Let ai(0,), i=1,2,,n, and αi[0,1], i=1,2,,n, be such that α1+α2++αn=1. Then (4)a1α1a2α2anαnα1a1+α2a2++αnan.

Theorem 3.11. (Weighted Cauchy–Schwarz inequality) [7] Let ai,biR and miR+ for i=1,2,,n. Then: (5)(i=1naibimi)2(i=1nai2mi)(i=1nbi2mi), with equality if and only if a1b1=a2b2==anbn.

4. Deriving the pathway energy boundaries on flower graphs families

The different pathway energy extremities such as lower, upper, improved upper, and improved lower bounds for the flower graph families are explored in this section.

Proposition 4.1. If μ1,μ2,,μn1,μn,μn+1,,μ2n+1 are the characteristic values of Ap(Fn) then,

i=12n+1μi2=4Λ+3+2.

Proof. Let us examine the vertex-disjoint pathway matrix Ap(Fn) associated with a flower graph. The elements of this matrix can be expressed in a structured manner:

Ap(Fn)={ωij=0,sum of all null entries on the maindiagonal where i=j,Λij=4,max disjoint paths between innerblock,if2in+1,2jn+1,ij=3,min disjoint paths in the inner blockwhere ij, i,jn+1,ij=2,disjoint paths between inner and outerblocksifin+2, 1j2n+1,1in+1,jn+2 The following equation defines the characteristic polynomial of this 2n+1×2n+1 square matrix: a0μ2n+1+a1μ2n+a2μ2n1++an=0, where the characteristic values are denoted as μ1,μ2,,μn1,μn,μn+1,,μ2n+1. The squared characteristic values added together can be expressed as follows: i=12n+1μi2=[i=j2n+1(ωij)]+[i<jn+1(ij)+i>jn+1(ij)]+[i2n+1j2n+1(Λij)]+[(i=1nj=n+12n+1(ij))+(i=n+12n+1j=12n+1(ij))+(i=n+12n+1j=n+12n+1(ij))]=4Λ+3+2. Here Λ,, and  denotes the sum of all the elements 4, 3 and 2 vertex-disjoint path matrix respectively. ◻

4.1. The pathway energy lower bounds for flower graph

Theorem 4.2. For a flower graph Fn, n4, with l=2n+1 vertices and 4n edges.

  1. The lower bound of pathway energy is given by: Ep(Fn)4Λ+3+2+2(l)(l1)i=1l(μiwi)2, where wi are the weights, i=1lwi=1 gives the total sum of the characteristic value weights.

  2. The improved lower bound of pathway energy is: Ep(Fn)4Λ+3+2+(l)(l1)D2lwhereD=|detAp(Fn)|.

Proof. Consider the flower graph Fn with an vertex-disjoint pathway matrix of order l×l, where l=2n+1 represents the vertices. The characteristic values μ1,μ2,,μl are obtained by solving the characteristic polynomial |Ap(Fn)μI|=0. The pathway energy Ep(Fn) is the sum of the absolute values of the characteristic values of the vertex-disjoint path matrix. The following condition describes this. 2=(i=1l|μi|)2.

Moreover, this can also be written as the product of the absolute characteristic value summations:

[Ep(Fn)]2=(i=1l|μi|)(j=1l|μj|).

[Ep(Fn)]2=(i=1l|μi|2)+(ij|μi||μj|).

Case 1: Proof for the pathway energy lower bounds of flower graph

From the Chebyshev’s Inequality 3, we derive that, 2i=1l|μi|2+2l(l1)(i=1l|μi|)(i=1l|μi|).

From the Weighted AM–GM inequality 4, we conclude, [Ep(Fn)]2i=1l|μi|2+2l(l1)(i=1lμiwi)(i=1lμiwi)wherei=1lwi=1,i=1l|μi|2+2l(l1)i=1l(μiwi)i=1l(μiwi),4Λ+3+2+2l(l1)i=1l(μiwi)2.…………. [by Theorem 4.1].

Thus, the lower bounds of the pathway energy for flower graph is, Ep(Fn)4Λ+3+2+2l(l1)i=1l(μiwi)2.

Case 2: Proof for the pathway energy improved lower bounds.

From the AM-GM inequalities in Eq. (2), we derive that 1l(l1)ij|μi||μj|(ij|μi||μj|)1l(l1),

[Ep(Fn)]2i=1l|μi|2+l(l1)(ij|μi||μj|)1l(l1)=i=1l|μi|2+l(l1)|i=1l(μi)|2l=4Λ+3+2+l(l1)D2lby Theorem 4.1.

Thus, the improved lower bounds of the pathway energy for flower graph is, Ep(Fn)4Λ+3+2+l(l1)D2l. ◻

Observation 4.3. The pathway energy of lower bounds, improved lower bounds and time complexity analysis O(n3) for flower graphs with n varying from 4 to 100 are computed and plotted in Figure 1: (a) and (b).

Figure 1 The comparison of path energy bounds (a) and Time complexity execution (b) for ower graphs

4.2. The pathway energy upper bound for flower graph

Theorem 4.4. For flower graph Fn with n4,

  1. The upper bound of pathway energy is given by: Ep(Fn)l(4Λ+3+2)

  2. The improved upper bound of pathway energy is: Ep(Fn)5(4Λ+3+2).

Proof. The methodology employed to ascertain the characteristic values echoes that utilized in Theorem 4.2. Let μ1μ2μ3μn1μnμl denote the characteristic values of the l×l vertex-disjoint path matrix of Fn.

Case 1: Proof for the pathway energy upper bound of flower graph.

From the Cauchy-Schwarz inequality in the Eq. (1) we derive that, (i=1lαiβi)2(i=1lαi2)(i=1lβi2).

To establish the upper bound, consider the expression [Ep(Fn)]2(i=1lαiβi)2, where the pathway energy is bounded by the right-hand side. Substituting αi=1 and βi=|μi| into the inequality yields the desired result.

2(i=1l1.|μi|)2(i=1l1)2.(i=1l|μi|2)……………… by 1),=l(4Λ+3+2)…………………. by Theorem 4.1,[Ep(Fn)]l(4Λ+3+2).

Thus, the upper bound of the pathway energy of the flower graph concluded by, Ep(Fn)l(4Λ+3+2).

Case 2: Proof for the pathway energy improved upper bound.

The Weighted Cauchy Schwarz inequality in (5) allows us to deduce that,

(i=1laibiwi)2(i=1lai2wi)(i=1lbi2wi).

For proving the improved upper bound, consider [Ep(Fn)]2(i=1lai.bi.wi)2, such that the pathway energy of the graph is less than RHS of the inequality, and substituting ai=1(l)32|μi| and bi=1 wi=5, in the above inequality,

2(i=1lμi2(l)3.5)(i=1l1.5),5ll3(i=1lμi2).l25,=5(4Λ+3+2)……………………. by Theorem 4.1,[Ep(Fn)]5(4Λ+3+2).

Thus, the improved upper bound of the pathway energy for flower graph is, [Ep(Fn)]5(4Λ+3+2). ◻

Observation 4.5. The pathway energy of upper bounds, improved upper bounds and time complexity analysis O(n3) for flower graphs with n varying from 4 to 100 are computed and plotted in Figure 1: (a) and (b).

5. The Pathway energy boundaries on sunflower graph

The different pathway energy bounds of sunflower graph SFn like lower, upper, improved lower, and improved upper bounds are investigated in this section.

Proposition 5.1. The characteristic values of Ap(SFn) are i=12n+1μi2=4δ+3ϰ+2ϖ, if
μ1,μ2,,μn1,μn,μn+1,,μ2n+1 are the characteristic values of Ap(SFn).

Proof. The structure of the vertex-disjoint path matrix Ap(SFn) for the sunflower graph is depicted as follows,

Ap(SFn)={ϝij=0,Total count of zeros positioned along themain diagonali=j,δij=4,Largest set of disjoint paths inside thecentral block, where |ij|=1 or |ij|=n1, 1i,jn+1,ϰij=3,the inner block's minimum disjointpath ifij, i,jn+1,ϖij=2,vertex-disjoint paths spanning the innerand outer regionsifin+2, 1j2n+1,1in+1,jn+2 The characteristic equation of this 2n+1×2n+1 square matrix is given by: a0μ2n+1+a1μ2n+a2μ2n1++an=0, where the characteristic values are denoted as μ1,μ2,,μn1,μn,μn+1,,μ2n+1. The sum of the squares of these characteristic values is defined as: i=12n+1μi2=[i=j2n+1(ϝij)]+[i<jn+1(ϰij)+i>jn+1(ϰij)]+[1in|ij|=11jn|ij|=n1(δij)]+[(i=1nj=n+12n+1(ϖij))+(i=n+12n+1j=12n+1(ϖij))+(i=n+12n+1j=n+12n+1(ϖij))]=4δ+3ϰ+2ϖ.

In this instance, δ,ϰ, and φ denote the total of all elements 4, 3, and 2 respectively, present in the vertex-disjoint path matrices. ◻

5.1. The pathway energy lower bounds for sunflower graph

Theorem 5.2. For a sunflower graph SFn with n5, there are l=2n+1 vertices and 4n edges.

  1. The lower bound of pathway energy is given by: Ep(SFn)4δ+3ϰ+2ϖ+2l(l1)i=1l(μiwi)2, where wi are the weights, i=1lwi=1 gives the total sum of the characteristic value weights.

  2. The improved lower bound of pathway energy is: Ep(SFn)4δ+3ϰ+2ϖ+(l)(l1)D2lwhereD=|detAp(SFn)|.

Proof. The proof is similar to Theorem 4.2 and is left to the interest of the reader. ◻

Observation 5.3. The pathway energy of lower bounds, improved lower bounds and time complexity analysis O(n3) for sunflower graphs with order of n varying from 5 to 100 are shown in Figure 2: (a) and (b).

Figure 2 The comparison of path energy bounds (a) and Time complexity execution (b) for sunower graphs

5.2. The pathway energy upper bound for sunflower graph

Theorem 5.4. For sunflower graph SFn with n5,

  1. The upper bound of pathway energy is given by: Ep(SFn)l(4δ+3ϰ+2ϖ)

  2. The improved upper bound of pathway energy is: Ep(SFn)5(4δ+3ϰ+2ϖ).

Proof. The proof is similar to Theorem 4.4 and is left to the interest of the reader. ◻

Observation 5.5. The pathway energy of upper bounds, improved upper bounds and time complexity analysis O(n3) for sunflower graphs with order of n varying from 5 to 100 are shown in Figure 2: (a) and (b).

6. The Path energy bounds on closed sunflower graph

This section explicates the distinct path energy bounds for the closed sunflower graph CSFn, comprising the lower, upper, exact energy, improved lower and upper bound.

Proposition 6.1. If μ1,μ2,,μn1,μn,μn+1,,μ2n+1 are the characteristic values of Ap(CSFn) then, i=12n+1μi2=5κ+4χ.

Proof. The arrangement of elements in the vertex-disjoint path matrix Ap(CSFn) of a closed sunflower graph is shown below:

Ap(SFn)={λij=0,Sum of zeros on the matrix's maindiagonal where  i=j,κij=5,Optimal disjoint path count within theinner blockwhereij, i,jn+1,χij=4,maximum possible disjoint paths between outerblock,ifin+2, 1j2n+1,1in+1,jn+2.

The characteristic equation associated with this 2n+1×2n+1 square matrix is: a0μ2n+1+a1μ2n+a2μ2n1++an=0, where the characteristic values are denoted as μ1,μ2,,μn1,μn,,μ2n+1.
The squared sum of these characteristic values is expressed as, i=12n+1μi2=[i=j2n+1(λij)]+[i<jn+1(κij)+i>jn+1(κij)]+[(i=1nj>n2n+1(χij))+(i>n2n+1j=12n+1(χij))+(i>n+12n+1j>n+12n+1(χij))]= 0(α)+5(κ)+4(χ)= 5κ+4χ.In this context, κ and χ represent the sums of all the elements 5 and 4 in the path matrices, respectively. ◻

6.1. The path energy lower bound for the closed sunflower graph

Theorem 6.2. Let CSFn be a closed sunflower graph comprising l=2n+1 vertices and 5n edges.

  1. The lower bound of pathway energy is given by, Ep(CSFn) 5κ+4χ+2l(l1)i=1l(μiwi)2, where wi is the weights of the characteristic values and their sum is i=1lwi=1.

  2. The improved pathway energy lower bound is given by, Ep(CSFn) 5κ+4χ+l(l1)D2lwhere D=|detAp(CSFn)|.

Proof. The vertex-disjoint path matrix of the closed sunflower network CSFn has order l×l, where the vertices are represented by l=2n+1. Solving the polynomial equation |Ap(CSFn)μI|=0 yields the characteristic values μ1,μ2,,μl. Following the method in Theorem 4.2 and using terminology that has already been explained, the pathway energy Ep(CSFn) is defined as the total of the absolute values of these characteristic values.

[Ep(CSFn)]2=(i=1l|μi|)2+(ij|μi||μj|).

Case 1: Proof for the pathway energy lower bound of CSFn

From the Chebyshev’s Inequality (3), we derive that, 2i=1l|μi|2+2l(l1)(i=1l|μi|)(i=1l|μi|).

From the Weighted AM–GM inequality (4), we conclude, [Ep(CSFn)]2i=1l|μi|2+2l(l1)(i=1lμiwi)(i=1lμiwi)wherei=1lwi=1,i=1l|μi|2+2l(l1)i=1l(μiwi)i=1l(μiwi) 5κ+4χ+2l(l1)i=1l(μiwi)2……………. by (Theorem6.1).

Thus, the lower bound is Ep(CSFn) 5κ+4χ+2l(l1)i=1l(μiwi)2.

Case 2: Proof for the pathway energy improved lower bound.

From the AM-GM inequalities in Eq. (2), we derive that

[Ep(CSFn)]2=i=1l|μi|2+l(l1)|i=1l(μi)|2l= 5κ+4χ+l(l1)D2l[by Theorem6.1].

Thus, the improved lower bound of the pathway energy for closed sunflower graph is, Ep(CSFn)5κ+4χ+l(l1)D2l. ◻

Observation 6.3. The pathway energy of lower bounds, improved lower bounds and time complexity analysis O(n3) for closed sunflower graphs with order of n varying from 5 to 100 are depicted in Figure 3: (a) and (b).

Figure 3 The comparison of path energy bounds (a) and time complexity execution (b) for closed sunower graphs

6.2. The exact pathway energy bound for closed sunflower graph

Theorem 6.4. For the closed sunflower graph CSFn, where n5, the exact bounds on the pathway energy are as follows: Ep[CSFn]=(9n4)+(n10)(0.47)+(0.47)+(n10)(8.53)+85.53 corrected to two decimal places.

Proof. The vertex-disjoint path configuration of the CSFn graph is elaborated in detail in the path adjacency matrix (6). It has 2n+1 roots, implying that it contains 2n+1 characteristic values.

The characteristic equation of (6) is (7)(μ)2n+1+tr(μ)2n++det(Ap(CSFn))=0.

Upon solving the Eq. (7), the 2n+1 characteristic values are determined to be,

μ1=μ2=μ3==μn1=5,μn=μn+1=μn+2==μ2n1=4, μ2n=(n10)(0.47)+0.47, and μ2n+1=(n10)(8.53)+83.53.

The Spectrum is expressed in the form of, Spec(Ap(CSFn))=[54(n10)(0.47)+(0.47)(n10)(8.53)+83.53nn111].

The exact closed sunflower graph pathway energy is given by, Ep[(CSFn)]=i=12n+1|μi|=∣5(n)+4(n1)+(n10)(0.47)0.47+(n10)(8.53)+85.53=9n4+(n10)(0.47)+(0.47)+(n10)(8.53)+85.53.

The value 5 occurs (n) times, 4 repeated (n1) times, [(n10)(0.47)]0.47, and [(n10)(8.53)]+85.53 arrives once.

Therefore the pathway energy exact bound for closed sunflower graph is denoted by Ep(CSFn)=9n4+(n10)(0.47)+(0.47)+(n10)(8.53)+85.53. ◻

Observation 6.5. The pathway exact energy and time complexity analysis O(n3) for closed sunflower graphs with order of n varying from 5 to 100 are shown in Figure 3: (a) and (b).

6.3. The path energy upper bound for closed sunflower graph

Theorem 6.6. For Closed sunflower CSFn with n5,

  1. The upper bound of pathway energy is given by: Ep(CSFn)l(5κ+4χ)

  2. The improved upper bound of pathway energy is: Ep(CSFn)5(5κ+4χ).

Proof. In this segment to establish the upper bounds, follow the approach of characteristic values determination in Theorem 4.2. For the purpose of the proof, it is a essential to take into account the following consideration,

Case 1: Proof for the pathway energy upper bound of CSFn.

To establish the upper bound, apply the Cauchy-Schwarz inequality in (1).

Consider [Ep(CSFn)]2(i=1lαiβi)2, where the pathway energy is bounded above. Substituting αi=1 and βi=|μi| into this inequality yields the desired result.

2(i=1l1.|μi|)2(i=1l1)2.(i=1l|μi|2)……………….. [by(1)]=l(5κ+4χ)…………………… [by Theorem 6.1][Ep(CSFn)]l(5κ+4χ).

Thus, the upper bound of the pathway energy of the closed sunflower graph concluded by, Ep(CSFn)l(5κ+4χ).

Case 2: Proof for the pathway energy improved upper bound.

Using the Weighted Cauchy-Schwarz inequality from Eq. (5), we deduce the improved upper bound: [Ep(CSFn)]2(i=1laibiwi)2 Substituting ai=1l3/2|μi|, bi=1, and wi=5 in RHS gives the result.

[Ep(CSFn)]2(i=1lμi2(l)3.5)(i=1l1.5)=5(5κ+4χ) …………………………. [by Theorem 6.1][Ep(CSFn)]5(5κ+4χ).

The improved upper bound of the path energy for the closed sunflower graph is: [Ep(CSFn)]5(5κ+4χ). ◻

Observation 6.7.The pathway energy of upper bounds, improved upper bounds and time complexity analysis O(n3) for closed sunflower graphs with order of n varying from 5 to 100 are depicted in Figure 3: (a) and (b).

Proof. The configuration of the vertex-disjoint path adjacency matrix Ap(Bln) for a blossom graph is outlined as follows,(8)Ap(Bln)={αij=0,whenever i=j,βij=5,whenever. ij,i,j2n+1. here ϱ1=i=j2n+1(αij),ϱ2=i<j(βij)+i>j(βij).

For this 2n+1×2n+1 matrix, the characteristic equation is, a0μ2n+1+a1μ2n+a2μ2n1++an=0. All the characteristic values are represented by μ1,μ2,,μn1,μn,μn+1,,μ2n+1.

The total of the squared characteristic values can be outlined as, i=12n+1μi2=i=j2n+1(aij)+i<j(bij)+i>j(bij)=i<j(bij)2+i>j(bij)2i=12n+1μi2=5[ϱ1+ϱ2] where ϱ1 and ϱ2 are specific terms related to the matrix components. ◻

7.1. The pathway energy lower bound for the blossom graph

Theorem 7.2. Let be a Bln blossom graph comprising l=2n+1 vertices and 6n edges.

  1. The lower bounds of pathway energy is given by,

    Ep(Bln)5(ϱ1+ϱ2)+2l(l1)i=1l(μiwi)2, where wi are the weights, i=1lwi=1 gives the total sum of the characteristic value weights.

  2. The improved pathway energy lower bound is given by, Ep(Bln)5(ϱ1+ϱ2)+l(l1)D2lwhereD=|detAp(Bln)|.

Proof. In general, the blossom graph Bln has a vertex-disjoint adjacency matrix of order l×l, with the number of vertices denoted by l=2n+1. The characteristic values μ1,μ2,,μl can be determined by solving |Ap(Bln)μI|=0. As similar to the method earlier in Theorem 4.2, the pathway energy Ep(Bln), is the total of the absolute values of these characteristic values.

[Ep(Bln)]2=(i=1l|μi|)2+(ij|μi||μj|).

Case 1: Proof for the pathway energy lower bound of blossom graph

From the Chebyshev’s Inequality (3), we derive that, 2i=1l|μi|2+2l(l1)(i=1l|μi|)(i=1l|μi|).

We derive the following from the Weighted AM–GM inequality (4): [Ep(Bln)]2i=1l|μi|2+2l(l1)(i=1lμiwi)(i=1lμiwi)wherei=1lwi=1,i=1l|μi|2+2l(l1)i=1l(μiwi)i=1l(μiwi)5(ϱ1+ϱ2)+2l(l1)i=1l(μiwi)2 by Theorem7.1.

Thus, the lower bound of the pathway energy for blossom graph is,

Ep(Bln)5(ϱ1+ϱ2)+2l(l1)i=1l(μiwi)2.

Case (ii): Proof for the pathway energy improved lower bound.

We obtain that from the AM-GM inequality in Eq. (2). [Ep(Bln)]2=i=1l|μi|2+l(l1)|i=1l(μi)|2l=5(ϱ1+ϱ2)+l(l1)D2lby Theorem 7.1.

Thus, the improved lower bound of the pathway energy for blossom graph is, Ep(Bln)5(ϱ1+ϱ2)+l(l1)D2l. ◻

Observation 7.3. The pathway energy of lower bounds, improved lower bounds and time complexity analysis O(n3) for blossom graphs with order of n varying from 5 to 100 are plotted in Figure 4: (a) and (b).

Figure 4 The comparison of path energy bounds (a) and time complexity execution (b) for blossom graphs

7.2. The pathway energy exact bound for blossom graph

Theorem 7.4. The defined bounds for the pathway energy in the blossom graph Bln, under the condition that n5, are Ep(Bln)=10(2n).

Proof. The Eq. (8) provides a detailed description of the pathway configuration for the vertex-disjoint matrix of the blossom graph. Solving the characteristic equation (μ)2n+1+tr(μ)2n++detAp(Bln)=0 derives the 2n+1 characteristic values in this way: μ1=μ2=μ3==μ2n=5andμ2n+1=5(2n).

The spectrum can be articulated as: Spec(Ap(Bln)) = [55(2n)2n1].

The exact energy path of the blossom graph provided by, Ep(Bln)=i=12n+1|μi|=5(2n)+5(2n)=3(2n1)+3(2n1)=10(2n). The term |5| appears 2n times, while 5(2n) appears once. Consequently, the exact pathway energy bound for the blossom graph is given by: Ep(Bln)=10(2n). ◻

Observation 7.5. The exact path energy and time complexity analysis O(n3) for blossom graphs with n varying from 5 to 100 are plotted in Figure 4: (a) and (b).

7.3. The pathway energy upper bound for blossom graph

Theorem 7.6. For blossom graph Bln with n5,

  1. The upper bound of pathway energy is given by: Ep(Bln)5l(ϱ1+ϱ2)

  2. The improved upper bound of pathway energy is: Ep(Bln)5(5(ϱ1+ϱ2)).

Proof. This section of the proof establishes the upper bounds using an analogous method of determining characteristic values as in Theorem 4.2.

Case 1: Proof for the path energy upper bound of blossom graph.

For deriving the upper bound Cauchy-Schwarz Inequality (1) leads that, [Ep(Bln)]2(i=1lαiβi)2, where the pathway energy is constrained by the right-hand side. Substituting αi=1 and βi=|μi| leads to the desired conclusion, [Ep(Bln)]2(i=1l1.|μi|)2(i=1l1)2.(i=1l|μi|2)……………………. by(1)=5l(ϱ1+ϱ2)……………………………. by Theorem 7.1[Ep(Bln)]5l(ϱ1+ϱ2)).

Thus, the upper bounds of the pathway energy of the blossom graph concluded by Ep(Bln)5l(ϱ1+ϱ2). Case 2: Proof for the pathway energy improved upper bound.

The Weighted Cauchy Schwarz inequality 5 allows us to deduce that, [Ep(Bln)]2(i=1lai.bi.wi)2.

By substituting ai=1(l)32|μi|, bi=1 and wi=5, in the above inequality, [Ep(Bln)]2(i=1lμi2(l)3.5)(i=1l1.5)=5(5(ϱ1+ϱ2))…………………….by Theorem 7.1[Ep(Bln)]5(5(ϱ1+ϱ2)).

Thus, the improved upper bound of the pathway energy for blossom graph is, [Ep(Bln)]5(5(ϱ1+ϱ2)). ◻

Observation 7.7. The pathway energy of upper bounds, improved upper bounds and time complexity analysis O(n3) for blossom graphs with order of n varying from 5 to 100 are plotted in Figure 4: (a) and (b).

8. Complexity analysis of flower families

We undertook a comprehensive computational analysis of flower families, employing algorithmic techniques to quantify the energy of these graphs alongside the time taken for each calculation. By plotting energy against computation time, we meticulously assessed the complexity and efficiency inherent in each graph type. Our results reveal that sunflower graphs exhibit a significantly higher complexity compared to the flower families under investigation. Notably, the computational time for sunflower graphs adheres to a complexity of O(n3), underscoring its critical nature in relation to the flower families discussed in this study.

9. Conclusion

This paper presents an innovative algorithmic framework for analyzing pathway energy within flower families, encompassing a wide range of graph types. We established precise limits for pathway energies and conducted an in-depth analysis of time complexity, illuminating significant computational challenges in this domain. The hallmark of our work is the enhanced efficiency and versatility of our pathway energy calculations, providing a robust tool for addressing complex spectral graph problems. These findings pave the way for future research focused on optimizing algorithms and exploring new classes of graphs. Moreover, this research has substantial practical implications for network optimization, improving algorithmic efficiency, and advancing spectral graph theory. Ultimately, our contributions propel the progress of computational graph theory and its related fields.

References:

  1. C. Adiga, E. Sampathkumar, M. A. Sriraj, and A. S. Shrikanth. Color energy of a graph. Proceedings of the Jangjeon Mathematical Society, 16(3):335–351, 2013.
  2. S. Akbari, A. Alazemi, M. Andelic, and M. A. Hosseinzadeh. On the energy of line graphs. Linear Algebra and Its Applications, 636:143–153, Mar. 2022. https://doi.org/10.1016/j.laa.2021.11.022.
  3. S. Akbari, M. Ghahremani, S. K. Hosseinzadeh, M. A. Ghezelahmad, H. Rasouli, and A. Tehranian. A lower bound for graph energy in terms of minimum and maximum degrees. MATCH Communications in Mathematical and in Computer Chemistry, 86:549–558, 2021.
  4. R. Arundhadhi and V. Ilayarani. Total coloring of closed helm, flower, and bistar graph family. International Journal of Scientific and Research Publications, 7(7):616–621, Jan. 2017. http://dx.doi.org/10.48550/arXiv.1801.00468.
  5. R. Balakrishnan and K. Ranganathan. A Textbook of Graph Theory. Springer New York, NY, 2000. https://doi.org/10.1007/978-1-4614-4529-6.
  6. Ş. B. Bozkurt Altındağ, E. Milovanović, M. Matejić, and I. Milovanović. Remarks on the bounds of graph energy. Communications in Combinatorics and Optimization:1–16, July 2024. https://doi.org/10.22049/cco.2024.28825.1739.
  7. Z. Cvetkovski. Inequalities: theorems, techniques, and selected problems. Springer Science & Business Media, Springer Berlin, Heidelberg, 2012.
  8. S. N. Daoud and Mohamed. The complexity of some families of cycle-related graphs. Journal of Taibah University for Science, 11(2):205–228, Apr. 2017. https://doi.org/10.1016/j.jtusci.2016.04.002.
  9. S. Duraj, P. Kopeć, M. Kubale, and T. Pikies. Scheduling of identical jobs with bipartite incompatibility graphs on uniform machines computational experiments. Decision Making in Manufacturing and Services, 11(1-2):53–61, 2017. https://doi.org/10.7494/dmms.2017.11.1-2.53.
  10. I. Gutman. Graph energy and nullity. Open Journal of Discrete and Applied Mathematics, 4:25–28, Mar. 2021. https://doi.org/10.30538/psrp-odam2021.0051.
  11. I. Gutman and B. Furtula. Survey of graph energies. Mathematics Interdisciplinary Research, 2(2):85–129, Dec. 2017. https://doi.org/10.22052/mir.2017.81507.1057.
  12. I. Gutman and H. Ramane. Research on graph energies in 2019. MATCH Communications in Mathematical and in Computer Chemistry, 84(2):277–292, 2020.
  13. F. Hutter, L. Xu, H. H. Hoos, and K. Leyton-Brown. Algorithm runtime prediction: methods and evaluation. Artificial Intelligence, 206:79–111, Jan. 2014. https://doi.org/10.1016/j.artint.2013.10.003.
  14. R. Jerlinkasmir, J. Venistine V, and S. Jebisha E. The several bounds of path energy for the network of wheel families. Montes Taurus Journal of Pure and Applied Mathematics, 6:37–56, 2024.
  15. I. Mezić, V. A. Fonoberov, T. Fonoberova, and M. Sahai. Spectral complexity of directed graphs and application to structural decomposition. Complexity, 1:9610826, Jan. 2019. https://doi.org/10.1155/2019/9610826.
  16. S. Naduvath, K. P. Chithra, and E. A. Shiny. On equitable coloring parameters of certain wheel-related graphs. Contemporary Studies In Discrete Mathematics, 1(1):3–12, Jan. 2017. http://dx.doi.org/10.48550/arXiv.1801.00468.
  17. S. C. Patekar and M. M. Shikare. On the path energy of some graphs. Journal of Mathematics and Computer Science, 10(3):535–543, Feb. 2020. https://doi.org/10.28919/jmcs/4460.
  18. A. Raza, M. Munir, T. Abbas, S. M. Eldin, and I. Khan. Spectrum of prism graph and relation with network-related quantities. AIMS Math, 8(2):2634–2647, Nov. 2023. http://dx.doi.org/10.3934/math.2023137.
  19. S. Sabeti and S. M. Semnani. On P(k) path eigenvalues and P(k) path energy of graphs. Discrete Mathematics, Algorithms and Applications, 15(8):2250170, Feb. 2023. https://doi.org/10.1142/S1793830922501701.
  20. M. M. Shikare, S. C. Malavadkar, P. P. Patekar, and I. Gutman. On path eigenvalues and path energy of graphs. MATCH Communications in Mathematical and in Computer Chemistry, 79(2):387–398, 2018.
  21. J. Simonsson, K. T. Atta, and W. Birk. A graph theoretical approach to modeling of district energy networks. IEEE Transactions on Control Systems Technology, 32(5):1616–1630, Jan. 2024. https://doi.org/10.1109/TCST.2023.3345213.
  22. B. Xu and L. Zhou. The path-index of a graph. Applied Mathematics and Computation, 461:128312, Jan. 2024. https://doi.org/10.1016/j.amc.2023.128312.
  23. L. Xueliang, Y. Shi, and I. Gutman. Graph energy. Springer Science and Business Media, Springer New York, NY, Aug. 2012. https://doi.org/10.1007/978-1-4614-4220-2.
  24. L. Ye. On the energy of a graph and its edge-deleted subgraphs. MATCH Communications in Mathematical and in Computer Chemistry, 92(2):417–423, 2024. https://doi.org/10.46793/match.92-2.417Y.