Pub Date : 2025-02-27DOI: 10.1016/j.dam.2025.02.030
Tomáš Madaras, Alfréd Onderko
Motivated by the broad studies of various edge-coloring anti-Ramsey-like problems where particular subgraphs are forbidden to be colored in a rainbow way or using many colors in general, we investigate edge-colorings with the constraint that each cycle sees at most colors, for a given positive integer . For such a coloring, the goal is to find the maximum number of colors, denoted by . We explore the basic properties and estimates of . A greedy-based general lower bound on this invariant is provided and its sharpness is discussed; we show that, for small values of , this bound is attained for highly connected graphs.
{"title":"On edge colorings of graphs with no color-rich cycles","authors":"Tomáš Madaras, Alfréd Onderko","doi":"10.1016/j.dam.2025.02.030","DOIUrl":"10.1016/j.dam.2025.02.030","url":null,"abstract":"<div><div>Motivated by the broad studies of various edge-coloring anti-Ramsey-like problems where particular subgraphs are forbidden to be colored in a rainbow way or using many colors in general, we investigate edge-colorings with the constraint that each cycle sees at most <span><math><mi>i</mi></math></span> colors, for a given positive integer <span><math><mi>i</mi></math></span>. For such a coloring, the goal is to find the maximum number of colors, denoted by <span><math><mrow><msubsup><mrow><mi>K</mi></mrow><mrow><mi>i</mi></mrow><mrow><mo>∘</mo></mrow></msubsup><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. We explore the basic properties and estimates of <span><math><mrow><msubsup><mrow><mi>K</mi></mrow><mrow><mi>i</mi></mrow><mrow><mo>∘</mo></mrow></msubsup><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span>. A greedy-based general lower bound on this invariant is provided and its sharpness is discussed; we show that, for small values of <span><math><mi>i</mi></math></span>, this bound is attained for highly connected graphs.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"368 ","pages":"Pages 105-111"},"PeriodicalIF":1.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510082","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1016/j.dam.2025.02.020
Huong Nguyen-Thu , Javad Tayyebi , Kien Trung Nguyen , Nguyen Thanh Luan
We investigate the quickest root–leaf interdiction problem on a tree, in which two players compete to achieve their objectives. The evader aims to escape the tree by traversing from the root to one of the leaves with the minimum transmission time, while the interdictor seeks to reduce the edge capacities within a given budget to maximize the transmission time of the evader in the perturbed tree. We prove that if the modifying cost is measured using the Hamming distance and the adjusted capacities are limited to a threshold, then there is an optimal solution, where the modified capacities are either equal to themselves or equal to the threshold. We also demonstrate that there are a linearly large number of values that can serve as candidates for the optimal objective. For each fixed value, we construct an auxiliary network in which its minimum cut is associated with the given value. The minimum cut approach helps to develop a combinatorial algorithm that solves the corresponding problem in time, where and are respectively the number of vertices and leaves in the underlying tree.
{"title":"The quickest root–leaf interdiction problem on tree networks","authors":"Huong Nguyen-Thu , Javad Tayyebi , Kien Trung Nguyen , Nguyen Thanh Luan","doi":"10.1016/j.dam.2025.02.020","DOIUrl":"10.1016/j.dam.2025.02.020","url":null,"abstract":"<div><div>We investigate the quickest root–leaf interdiction problem on a tree, in which two players compete to achieve their objectives. The evader aims to escape the tree by traversing from the root to one of the leaves with the minimum transmission time, while the interdictor seeks to reduce the edge capacities within a given budget to maximize the transmission time of the evader in the perturbed tree. We prove that if the modifying cost is measured using the Hamming distance and the adjusted capacities are limited to a threshold, then there is an optimal solution, where the modified capacities are either equal to themselves or equal to the threshold. We also demonstrate that there are a linearly large number of values that can serve as candidates for the optimal objective. For each fixed value, we construct an auxiliary network in which its minimum cut is associated with the given value. The minimum cut approach helps to develop a combinatorial algorithm that solves the corresponding problem in <span><math><mrow><mi>O</mi><mrow><mo>(</mo><mi>n</mi><mo>max</mo><mrow><mo>{</mo><mi>m</mi><mo>,</mo><mo>log</mo><mi>n</mi><mo>}</mo></mrow><mo>)</mo></mrow></mrow></math></span> time, where <span><math><mi>n</mi></math></span> and <span><math><mi>m</mi></math></span> are respectively the number of vertices and leaves in the underlying tree.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"368 ","pages":"Pages 91-104"},"PeriodicalIF":1.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1016/j.dam.2025.02.031
Zahid Raza , Shehnaz Akhter , Roslan Hasni
Chemical graph theory plays a crucial role in mathematical chemistry by using graph invariants to represent chemical phenomena in a mathematical framework. Topological descriptors, which are graph invariants formed from molecular graph representations of chemical compounds, are employed in QSPR and QSAR studies. The Zagreb connection indices are topological descriptors which are used to analyze graphs based on connection cardinality. They were introduced in 1972 to calculate the total electron energy of alternate hydrocarbons. Recently, they have gained renewed attention due to their ability to provide a more precise correlation for the physicochemical characteristics of different compounds compared to basic Zagreb indices. In this article, we aim to analyze and establish the correlations of the first Zagreb connection index and the total domination number of trees. Our focus is on providing a detailed description of trees having the largest first Zagreb connection index among trees that have a specific total domination number.
{"title":"Maximal first Zagreb connection index of trees with given total domination number","authors":"Zahid Raza , Shehnaz Akhter , Roslan Hasni","doi":"10.1016/j.dam.2025.02.031","DOIUrl":"10.1016/j.dam.2025.02.031","url":null,"abstract":"<div><div>Chemical graph theory plays a crucial role in mathematical chemistry by using graph invariants to represent chemical phenomena in a mathematical framework. Topological descriptors, which are graph invariants formed from molecular graph representations of chemical compounds, are employed in QSPR and QSAR studies. The Zagreb connection indices are topological descriptors which are used to analyze graphs based on connection cardinality. They were introduced in 1972 to calculate the total electron energy of alternate hydrocarbons. Recently, they have gained renewed attention due to their ability to provide a more precise correlation for the physicochemical characteristics of different compounds compared to basic Zagreb indices. In this article, we aim to analyze and establish the correlations of the first Zagreb connection index and the total domination number of trees. Our focus is on providing a detailed description of trees having the largest first Zagreb connection index among trees that have a specific total domination number.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"368 ","pages":"Pages 82-90"},"PeriodicalIF":1.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143512583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1016/j.dam.2025.02.027
Yuting Tian, Jianhua Tu
Let be the set of all maximal independent sets in a graph , and let . In this paper, we show that for any tree with vertices and independence number , and for any unicyclic graph with vertices and independence number , where represents the th Fibonacci number. Moreover, we also show that the above inequalities are sharp.
{"title":"The minimum number of maximal independent sets in graphs with given order and independence number","authors":"Yuting Tian, Jianhua Tu","doi":"10.1016/j.dam.2025.02.027","DOIUrl":"10.1016/j.dam.2025.02.027","url":null,"abstract":"<div><div>Let <span><math><mrow><mi>M</mi><mi>I</mi><mi>S</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> be the set of all maximal independent sets in a graph <span><math><mi>G</mi></math></span>, and let <span><math><mrow><mi>m</mi><mi>i</mi><mi>s</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>=</mo><mrow><mo>|</mo><mi>M</mi><mi>I</mi><mi>S</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>|</mo></mrow></mrow></math></span>. In this paper, we show that for any tree <span><math><mi>T</mi></math></span> with <span><math><mi>n</mi></math></span> vertices and independence number <span><math><mi>α</mi></math></span>, <span><span><span><math><mrow><mi>m</mi><mi>i</mi><mi>s</mi><mrow><mo>(</mo><mi>T</mi><mo>)</mo></mrow><mo>≥</mo><mi>f</mi><mrow><mo>(</mo><mi>n</mi><mo>−</mo><mi>α</mi><mo>+</mo><mn>2</mn><mo>)</mo></mrow><mo>,</mo></mrow></math></span></span></span>and for any unicyclic graph <span><math><mi>G</mi></math></span> with <span><math><mi>n</mi></math></span> vertices and independence number <span><math><mi>α</mi></math></span>, <span><span><span><math><mrow><mi>m</mi><mi>i</mi><mi>s</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>≥</mo><mfenced><mrow><mtable><mtr><mtd><mn>2</mn><mo>,</mo><mspace></mspace></mtd><mtd><mtext>if</mtext><mspace></mspace><mi>n</mi><mo>=</mo><mn>4</mn><mo>,</mo></mtd></mtr><mtr><mtd><mn>3</mn><mo>,</mo><mspace></mspace></mtd><mtd><mtext>if</mtext><mspace></mspace><mi>α</mi><mo>=</mo><mi>n</mi><mo>−</mo><mn>2</mn><mspace></mspace><mtext>and</mtext><mspace></mspace><mi>n</mi><mo>≠</mo><mn>4</mn><mo>,</mo></mtd></mtr><mtr><mtd><mn>2</mn><mi>f</mi><mrow><mo>(</mo><mi>n</mi><mo>−</mo><mi>α</mi><mo>)</mo></mrow><mo>,</mo><mspace></mspace></mtd><mtd><mtext>if</mtext><mspace></mspace><mi>n</mi><mo>≥</mo><mn>6</mn><mspace></mspace><mtext>and</mtext><mspace></mspace><mrow><mo>⌈</mo><mfrac><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></mfrac><mo>⌉</mo></mrow><mo>≤</mo><mi>α</mi><mo><</mo><mi>n</mi><mo>−</mo><mn>2</mn><mo>,</mo></mtd></mtr><mtr><mtd><mi>f</mi><mrow><mo>(</mo><mi>n</mi><mo>−</mo><mi>α</mi><mo>+</mo><mn>2</mn><mo>)</mo></mrow><mo>−</mo><mi>f</mi><mrow><mo>(</mo><mi>n</mi><mo>−</mo><mi>α</mi><mo>−</mo><mn>3</mn><mo>)</mo></mrow><mo>,</mo><mspace></mspace></mtd><mtd><mtext>if</mtext><mspace></mspace><mi>n</mi><mo>≥</mo><mn>5</mn><mo>,</mo><mspace></mspace><mtext>and</mtext><mspace></mspace><mi>n</mi><mspace></mspace><mtext>is odd</mtext><mo>,</mo><mspace></mspace><mtext>and</mtext><mspace></mspace><mi>α</mi><mo>=</mo><mrow><mo>⌊</mo><mfrac><mrow><mi>n</mi></mrow><mrow><mn>2</mn></mrow></mfrac><mo>⌋</mo></mrow><mo>,</mo></mtd></mtr></mtable></mrow></mfenced></mrow></math></span></span></span>where <span><math><mrow><mi>f</mi><mrow><mo>(</mo><mi>n</mi><mo>)</mo></mrow></mrow></math></span> represents the <span><math><mi>n</mi></math></span>th Fibonacci number. Moreover, we also show that the above inequalities are sharp.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"368 ","pages":"Pages 52-65"},"PeriodicalIF":1.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1016/j.dam.2025.02.018
Zai Ping Lu, Shu Dan Xue
<div><div>In this paper, we investigate Hamilton paths passing through a prescribed linear forest in a hybrid-faulty star graph. Let <span><math><mi>M</mi></math></span> be a matching with <span><math><mi>m</mi></math></span> edges of the star graph <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span>, <span><math><mi>F</mi></math></span> be an <span><math><mi>f</mi></math></span>-subset of <span><math><mrow><mi>E</mi><mrow><mo>(</mo><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>)</mo></mrow></mrow></math></span>, <span><math><mrow><mo>{</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>}</mo></mrow></math></span> be a 2-subset of <span><math><mrow><mi>V</mi><mrow><mo>(</mo><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>)</mo></mrow></mrow></math></span>, and <span><math><mi>L</mi></math></span> be a linear forest of <span><math><mrow><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>−</mo><mi>F</mi></mrow></math></span>. Suppose that <span><math><mrow><mi>m</mi><mo>+</mo><mi>f</mi><mo>≤</mo><mi>n</mi><mo>−</mo><mn>4</mn></mrow></math></span>, neither <span><math><mi>x</mi></math></span> nor <span><math><mi>y</mi></math></span> is an inner vertex of <span><math><mi>L</mi></math></span>, and <span><math><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></math></span> are not located on the same component of <span><math><mi>L</mi></math></span>. We prove that, for any <span><math><mrow><mi>w</mi><mo>∈</mo><mi>V</mi><mrow><mo>(</mo><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>)</mo></mrow><mo>∖</mo><mi>V</mi><mrow><mo>(</mo><mi>L</mi><mo>)</mo></mrow></mrow></math></span>, there exists a Hamilton path of <span><math><mrow><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>−</mo><mi>F</mi><mo>−</mo><mi>w</mi></mrow></math></span> between <span><math><mi>x</mi></math></span> and <span><math><mi>y</mi></math></span> passing through <span><math><mi>L</mi></math></span> provided that <span><math><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></math></span> belong to the partite set not containing <span><math><mi>w</mi></math></span>, and <span><math><mrow><mrow><mo>|</mo><mi>E</mi><mrow><mo>(</mo><mi>L</mi><mo>)</mo></mrow><mo>|</mo></mrow><mo>≤</mo><mi>n</mi><mo>−</mo><mn>4</mn><mo>−</mo><mi>m</mi><mo>−</mo><mi>f</mi></mrow></math></span>. As a consequence, if <span><math><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></math></span> are from opposite partite sets and <span><math><mrow><mrow><mo>|</mo><mi>E</mi><mrow><mo>(</mo><mi>L</mi><mo>)</mo></mrow><mo>|</mo></mrow><mo>≤</mo><mi>n</mi><mo>−</mo><mn>4</mn><mo>−</mo><mi>m</mi><mo>−</mo><mi>f</mi></mrow></math></
{"title":"On prescribed Hamilton laceability of hybrid-faulty star graphs","authors":"Zai Ping Lu, Shu Dan Xue","doi":"10.1016/j.dam.2025.02.018","DOIUrl":"10.1016/j.dam.2025.02.018","url":null,"abstract":"<div><div>In this paper, we investigate Hamilton paths passing through a prescribed linear forest in a hybrid-faulty star graph. Let <span><math><mi>M</mi></math></span> be a matching with <span><math><mi>m</mi></math></span> edges of the star graph <span><math><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub></math></span>, <span><math><mi>F</mi></math></span> be an <span><math><mi>f</mi></math></span>-subset of <span><math><mrow><mi>E</mi><mrow><mo>(</mo><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>)</mo></mrow></mrow></math></span>, <span><math><mrow><mo>{</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo>}</mo></mrow></math></span> be a 2-subset of <span><math><mrow><mi>V</mi><mrow><mo>(</mo><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>)</mo></mrow></mrow></math></span>, and <span><math><mi>L</mi></math></span> be a linear forest of <span><math><mrow><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>−</mo><mi>F</mi></mrow></math></span>. Suppose that <span><math><mrow><mi>m</mi><mo>+</mo><mi>f</mi><mo>≤</mo><mi>n</mi><mo>−</mo><mn>4</mn></mrow></math></span>, neither <span><math><mi>x</mi></math></span> nor <span><math><mi>y</mi></math></span> is an inner vertex of <span><math><mi>L</mi></math></span>, and <span><math><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></math></span> are not located on the same component of <span><math><mi>L</mi></math></span>. We prove that, for any <span><math><mrow><mi>w</mi><mo>∈</mo><mi>V</mi><mrow><mo>(</mo><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>)</mo></mrow><mo>∖</mo><mi>V</mi><mrow><mo>(</mo><mi>L</mi><mo>)</mo></mrow></mrow></math></span>, there exists a Hamilton path of <span><math><mrow><msub><mrow><mi>S</mi></mrow><mrow><mi>n</mi></mrow></msub><mo>−</mo><mi>V</mi><mrow><mo>(</mo><mi>M</mi><mo>)</mo></mrow><mo>−</mo><mi>F</mi><mo>−</mo><mi>w</mi></mrow></math></span> between <span><math><mi>x</mi></math></span> and <span><math><mi>y</mi></math></span> passing through <span><math><mi>L</mi></math></span> provided that <span><math><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></math></span> belong to the partite set not containing <span><math><mi>w</mi></math></span>, and <span><math><mrow><mrow><mo>|</mo><mi>E</mi><mrow><mo>(</mo><mi>L</mi><mo>)</mo></mrow><mo>|</mo></mrow><mo>≤</mo><mi>n</mi><mo>−</mo><mn>4</mn><mo>−</mo><mi>m</mi><mo>−</mo><mi>f</mi></mrow></math></span>. As a consequence, if <span><math><mrow><mi>x</mi><mo>,</mo><mi>y</mi></mrow></math></span> are from opposite partite sets and <span><math><mrow><mrow><mo>|</mo><mi>E</mi><mrow><mo>(</mo><mi>L</mi><mo>)</mo></mrow><mo>|</mo></mrow><mo>≤</mo><mi>n</mi><mo>−</mo><mn>4</mn><mo>−</mo><mi>m</mi><mo>−</mo><mi>f</mi></mrow></math></","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"368 ","pages":"Pages 72-81"},"PeriodicalIF":1.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143509641","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1016/j.dam.2025.02.022
Jan Kristian Haugland
We investigate the max min of the algebraic degree and the nonlinearity of a Boolean function in variables when restricted to a -dimensional affine subspace of . Previous authors have focused on the cases when the max min of the algebraic degree is 0 or 1. Upper bounds, lower bounds and a conjecture on the exact value in special cases are presented.
{"title":"On the max min of the algebraic degree and the nonlinearity of a Boolean function on an affine subspace","authors":"Jan Kristian Haugland","doi":"10.1016/j.dam.2025.02.022","DOIUrl":"10.1016/j.dam.2025.02.022","url":null,"abstract":"<div><div>We investigate the max min of the algebraic degree and the nonlinearity of a Boolean function in <span><math><mi>n</mi></math></span> variables when restricted to a <span><math><mi>k</mi></math></span>-dimensional affine subspace of <span><math><msubsup><mrow><mi>F</mi></mrow><mrow><mn>2</mn></mrow><mrow><mi>n</mi></mrow></msubsup></math></span>. Previous authors have focused on the cases when the max min of the algebraic degree is 0 or 1. Upper bounds, lower bounds and a conjecture on the exact value in special cases are presented.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"368 ","pages":"Pages 66-71"},"PeriodicalIF":1.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-27DOI: 10.1016/j.dam.2025.02.029
Xianglai Qi, Lingfa Lu, Shiguo Zhou
In this paper, we consider the online hierarchical scheduling for load balancing on two identical machines. In the problem, the jobs are available online over list and the objective is to minimize the -norm of every machine’s load. A best possible online algorithm is designed for this problem.
{"title":"A note on the online hierarchical scheduling for lp-norm load balancing","authors":"Xianglai Qi, Lingfa Lu, Shiguo Zhou","doi":"10.1016/j.dam.2025.02.029","DOIUrl":"10.1016/j.dam.2025.02.029","url":null,"abstract":"<div><div>In this paper, we consider the online hierarchical scheduling for load balancing on two identical machines. In the problem, the jobs are available online over list and the objective is to minimize the <span><math><msub><mrow><mi>l</mi></mrow><mrow><mi>p</mi></mrow></msub></math></span>-norm of every machine’s load. A best possible online algorithm is designed for this problem.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"368 ","pages":"Pages 45-51"},"PeriodicalIF":1.0,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-21DOI: 10.1016/j.dam.2025.02.017
Carl Johan Casselgren , Mesfin Masre
For a connected graph and , the general degree-eccentricity index of is defined as , where is the vertex set of , is the degree of a vertex and is the eccentricity of in , i.e. the maximum distance from to another vertex of the graph. This index generalizes several well-known ‘topological indices’ of graphs such as the eccentric connectivity index. We characterize the unique unicyclic graphs with the maximum and the minimum general degree-eccentricity index among all -vertex unicyclic graphs with fixed order, girth, and maximum degree for the cases and .
{"title":"General degree-eccentricity index of unicyclic graphs of given order, girth and maximum degree","authors":"Carl Johan Casselgren , Mesfin Masre","doi":"10.1016/j.dam.2025.02.017","DOIUrl":"10.1016/j.dam.2025.02.017","url":null,"abstract":"<div><div>For a connected graph <span><math><mi>G</mi></math></span> and <span><math><mrow><mi>a</mi><mo>,</mo><mi>b</mi><mo>∈</mo><mi>R</mi></mrow></math></span>, the general degree-eccentricity index of <span><math><mi>G</mi></math></span> is defined as <span><math><mrow><mi>D</mi><mi>E</mi><msub><mrow><mi>I</mi></mrow><mrow><mi>a</mi><mo>,</mo><mi>b</mi></mrow></msub><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>=</mo><msub><mrow><mo>∑</mo></mrow><mrow><mi>v</mi><mo>∈</mo><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></msub><msubsup><mrow><mi>d</mi></mrow><mrow><mi>G</mi></mrow><mrow><mi>a</mi></mrow></msubsup><mrow><mo>(</mo><mi>v</mi><mo>)</mo></mrow><mi>e</mi><mi>c</mi><msubsup><mrow><mi>c</mi></mrow><mrow><mi>G</mi></mrow><mrow><mi>b</mi></mrow></msubsup><mrow><mo>(</mo><mi>v</mi><mo>)</mo></mrow></mrow></math></span>, where <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow></mrow></math></span> is the vertex set of <span><math><mi>G</mi></math></span>, <span><math><mrow><msub><mrow><mi>d</mi></mrow><mrow><mi>G</mi></mrow></msub><mrow><mo>(</mo><mi>v</mi><mo>)</mo></mrow></mrow></math></span> is the degree of a vertex <span><math><mi>v</mi></math></span> and <span><math><mrow><mi>e</mi><mi>c</mi><msub><mrow><mi>c</mi></mrow><mrow><mi>G</mi></mrow></msub><mrow><mo>(</mo><mi>v</mi><mo>)</mo></mrow></mrow></math></span> is the eccentricity of <span><math><mi>v</mi></math></span> in <span><math><mi>G</mi></math></span>, i.e. the maximum distance from <span><math><mi>v</mi></math></span> to another vertex of the graph. This index generalizes several well-known ‘topological indices’ of graphs such as the eccentric connectivity index. We characterize the unique unicyclic graphs with the maximum and the minimum general degree-eccentricity index among all <span><math><mi>n</mi></math></span>-vertex unicyclic graphs with fixed order, girth, and maximum degree for the cases <span><math><mrow><mi>a</mi><mo>≥</mo><mn>1</mn><mo>,</mo><mi>b</mi><mo>≤</mo><mn>0</mn></mrow></math></span> and <span><math><mrow><mn>0</mn><mo>≤</mo><mi>a</mi><mo>≤</mo><mn>1</mn><mo>,</mo><mi>b</mi><mo>≥</mo><mn>0</mn></mrow></math></span>.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"368 ","pages":"Pages 30-44"},"PeriodicalIF":1.0,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-21DOI: 10.1016/j.dam.2025.02.006
Athmakoori Prashant , S. Francis Raj
In 1987, A. Gyárfás in his paper “Problems from the world surrounding perfect graphs” posed the problem of determining the smallest -binding function for , when is -bounded. So far the problem has only been attempted for some forest with four or five vertices. In this paper, we address the problem when and show that if is a -free graph with , then it admits as a -binding function. Moreover, we also construct examples to show that this bound is tight for all values of .
{"title":"An optimal chromatic bound for the class of {P3∪2K1,P3∪2K1¯}-free graphs","authors":"Athmakoori Prashant , S. Francis Raj","doi":"10.1016/j.dam.2025.02.006","DOIUrl":"10.1016/j.dam.2025.02.006","url":null,"abstract":"<div><div>In 1987, A. Gyárfás in his paper “Problems from the world surrounding perfect graphs” posed the problem of determining the smallest <span><math><mi>χ</mi></math></span>-binding function for <span><math><mrow><mi>G</mi><mrow><mo>(</mo><mi>F</mi><mo>,</mo><mover><mrow><mi>F</mi></mrow><mo>¯</mo></mover><mo>)</mo></mrow></mrow></math></span>, when <span><math><mrow><mi>G</mi><mrow><mo>(</mo><mi>F</mi><mo>)</mo></mrow></mrow></math></span> is <span><math><mi>χ</mi></math></span>-bounded. So far the problem has only been attempted for some forest <span><math><mi>F</mi></math></span> with four or five vertices. In this paper, we address the problem when <span><math><mrow><mi>F</mi><mo>=</mo><msub><mrow><mi>P</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>∪</mo><mn>2</mn><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow></math></span> and show that if <span><math><mi>G</mi></math></span> is a <span><math><mrow><mo>{</mo><msub><mrow><mi>P</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>∪</mo><mn>2</mn><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn></mrow></msub><mo>,</mo><mover><mrow><msub><mrow><mi>P</mi></mrow><mrow><mn>3</mn></mrow></msub><mo>∪</mo><mn>2</mn><msub><mrow><mi>K</mi></mrow><mrow><mn>1</mn></mrow></msub></mrow><mo>¯</mo></mover><mo>}</mo></mrow></math></span>-free graph with <span><math><mrow><mi>ω</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>≠</mo><mn>3</mn></mrow></math></span>, then it admits <span><math><mrow><mi>ω</mi><mrow><mo>(</mo><mi>G</mi><mo>)</mo></mrow><mo>+</mo><mn>1</mn></mrow></math></span> as a <span><math><mi>χ</mi></math></span>-binding function. Moreover, we also construct examples to show that this bound is tight for all values of <span><math><mrow><mi>ω</mi><mo>≠</mo><mn>3</mn></mrow></math></span>.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"367 ","pages":"Pages 226-234"},"PeriodicalIF":1.0,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143463599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-20DOI: 10.1016/j.dam.2025.02.005
Carl Kingsford , Guillaume Marçais
A multigraph is uniformly -edge-connected if there are exactly edge-disjoint paths between any pair of vertices. For example, a uniformly -edge-connected graph is obtained from a -edge-connected graph by collapsing the nodes connected by more than edge-disjoint paths into supernodes. We characterize the class of uniformly 3-edge-connected graphs, giving a synthesis involving two operations by which every uniformly 3-edge-connected multigraph can be generated. Slightly modified syntheses give the planar uniformly 3-edge-connected graphs and the uniformly 3-edge-connected graphs with the fewest possible edges, generalizing the well-known Harary graphs. In proving the correctness of the synthesis, we also show the existence of a particular type of induced, non-separating cycle in near 3-regular graphs, which is of interest in its own right.
{"title":"A synthesis for uniformly 3-edge-connected graphs","authors":"Carl Kingsford , Guillaume Marçais","doi":"10.1016/j.dam.2025.02.005","DOIUrl":"10.1016/j.dam.2025.02.005","url":null,"abstract":"<div><div>A multigraph is <em>uniformly</em> <span><math><mi>k</mi></math></span>-<em>edge-connected</em> if there are exactly <span><math><mi>k</mi></math></span> edge-disjoint paths between any pair of vertices. For example, a uniformly <span><math><mi>k</mi></math></span>-edge-connected graph is obtained from a <span><math><mi>k</mi></math></span>-edge-connected graph by collapsing the nodes connected by more than <span><math><mi>k</mi></math></span> edge-disjoint paths into supernodes. We characterize the class of uniformly 3-edge-connected graphs, giving a synthesis involving two operations by which every uniformly 3-edge-connected multigraph can be generated. Slightly modified syntheses give the planar uniformly 3-edge-connected graphs and the uniformly 3-edge-connected graphs with the fewest possible edges, generalizing the well-known Harary graphs. In proving the correctness of the synthesis, we also show the existence of a particular type of induced, non-separating cycle in near 3-regular graphs, which is of interest in its own right.</div></div>","PeriodicalId":50573,"journal":{"name":"Discrete Applied Mathematics","volume":"368 ","pages":"Pages 18-29"},"PeriodicalIF":1.0,"publicationDate":"2025-02-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"数学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}