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Tamkang Journal of Mathematics最新文献

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Biconservative Lorentz Hypersurfaces with at Least Three Principal Curvatures 具有至少三个主曲率的双保守洛伦兹超曲面
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-11-14 DOI: 10.5556/j.tkjm.54.2023.4876
F. Pashaie
{"title":"Biconservative Lorentz Hypersurfaces with at Least Three Principal Curvatures","authors":"F. Pashaie","doi":"10.5556/j.tkjm.54.2023.4876","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.4876","url":null,"abstract":"Biconservative submanifolds, with important role in mathematical physics and differential geometry, arise as the conservative stress-energy tensor associated to the variational problem of biharmonic submanifolds. Many examples of biconservative hypersurfaces have constant mean curvature. A famous conjecture of Bang-Yen Chen on Euclidean spaces says that everybiharmonic submanifold has null mean curvature. Inspired by Chen conjecture, we study biconservative Lorentz submanifolds of the Minkowski spaces. Although the conjecture has not been generally confirmed, it has been proven in many cases, and this has led to its spread to various types of submenifolds. As an extension, we consider a advanced version of the conjecture (namely, $L_1$-conjecture) on Lorentz hypersurfaces of the pseudo-Euclidean space $mathbb{M}^5 :=mathbb{E}^5_1$ (i.e. the Minkowski 5-space). We show every $L_1$-biconservative Lorentz hypersurface of $mathbb{M}^5$ with constant mean curvature and at least three principal curvatures has constant second mean curvature.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"19 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81755974","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Algorithm for Finite Family of Variational Inequality with Fixed Point of Two Non-expansive Mappings 两个非扩张映射的不动点变分不等式有限族的算法
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-10-20 DOI: 10.5556/j.tkjm.54.2023.4865
Monika Swami, S. Rathee
{"title":"Algorithm for Finite Family of Variational Inequality with Fixed Point of Two Non-expansive Mappings","authors":"Monika Swami, S. Rathee","doi":"10.5556/j.tkjm.54.2023.4865","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.4865","url":null,"abstract":"In the recent work, a new hybrid technique for computing the common solution of fixed point of a finite family of two non-expansive mapping and variational inequality problem for inverse strongly monotone mapping in a real Hilbert space is provided. We also demonstrate the convergence of the hybrid approach using an example.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"35 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85418114","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Adjoint Relations Between the Category of Poset Acts and Some Other Categories 后置行为范畴与其他范畴的伴随关系
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-10-15 DOI: 10.5556/j.tkjm.54.2023.4966
L. Shahbaz
{"title":"Adjoint Relations Between the Category of Poset Acts and Some Other Categories","authors":"L. Shahbaz","doi":"10.5556/j.tkjm.54.2023.4966","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.4966","url":null,"abstract":"In this paper, first the congruences in the category PosAct-S of all poset acts over a pomonoid S; an S-act in the category Pos of all posets, with action preserving monotone maps between them, are introduced. Then, we study the existence of the free and cofree objects in the category PosAct-S. More precisely, we consider all forgetful functors between this category and the categories Pos-S of all S-posets, Pos of all posets, Act-S of all S-acts, and Set of all sets, and we study the existence of their left and right adjoints. It is shown that the category Pos-S is a full reflective and coreflective subcategory of PosAct-S.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"179 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-10-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82685186","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Fitted Operator Average Finite Difference Method for Singularly Perturbed Delay Parabolic Reaction Diffusion Problems with Non-Local Boundary Conditions 非局部边界条件下奇摄动时滞抛物型反应扩散问题的拟合算子平均有限差分法
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-10-14 DOI: 10.5556/j.tkjm.54.2023.4175
Wakjira Tolassa Gobena, G. Duressa
{"title":"Fitted Operator Average Finite Difference Method for Singularly Perturbed Delay Parabolic Reaction Diffusion Problems with Non-Local Boundary Conditions","authors":"Wakjira Tolassa Gobena, G. Duressa","doi":"10.5556/j.tkjm.54.2023.4175","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.4175","url":null,"abstract":"This paper deals with numerical solution of singularly perturbed delay parabolic reaction diffusion problem having large delay on the spatial variable with non-local boundary condition. The solution of the problem exhibits parabolic boundary layer on both sides of the spatial domain and interior layer is also created. Introducing a fitting parameter into asymptotic solution and applying average finite difference approximation, a fitted operator finite difference method is developed for solving the problem under consideration. To treat the non-local boundary condition, Simpson's rule is applied. The stability and $varepsilon$ uniform convergence analysis has been carried out. To validate the applicability of the scheme, numerical examples are presented and solved for different values of the perturbation parameter $varepsilon$ and mesh sizes. The numerical results are tabulated in terms of maximum absolute errors and rate of convergence and it is observed that the present method is more accurate and shown to be second order Uniformly convergent in both direction, and it also improves the results of the methods existing in the literature.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"7 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81124628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 5
Refinements of Some Numerical Radius Inequalities for Hilbert Space Operators 希尔伯特空间算子若干数值半径不等式的改进
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-10-14 DOI: 10.5556/j.tkjm.54.2023.4061
M. Rashid
{"title":"Refinements of Some Numerical Radius Inequalities for Hilbert Space Operators","authors":"M. Rashid","doi":"10.5556/j.tkjm.54.2023.4061","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.4061","url":null,"abstract":"Some power inequalities for the numerical radius based on the recent Dragomir extension of Furuta's inequality are established. Some particular cases are also provided. Moreover, we get an improvement of the H\"older-McCarthy operator inequality in the case when $rgeq 1$ and refine generalized inequalities involving powers of the numerical radius for sums and products of Hilbert space operators.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"88 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"79978613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Solving Unconstrained Optimization Problems with Some Three-term Conjugate Gradient Methods 用三项共轭梯度法求解无约束优化问题
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-09-16 DOI: 10.5556/j.tkjm.54.2023.4185
Ladan Arman
{"title":"Solving Unconstrained Optimization Problems with Some Three-term Conjugate Gradient Methods","authors":"Ladan Arman","doi":"10.5556/j.tkjm.54.2023.4185","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.4185","url":null,"abstract":"In this paper, based on the efficient Conjugate Descent ({tt CD}) method, two generalized {tt CD}algorithms are proposed to solve the unconstrained optimization problems.These methods are three-term conjugate gradient methods which the generateddirections by using the conjugate gradient parameters and independent of the line searchsatisfy in the sufficient descent condition. Furthermore, under the strong Wolfe line search,the global convergence of the proposed methods are proved. Also, the preliminary numericalresults on the {tt CUTEst} collection are presented to show effectiveness of our methods.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"19 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74440709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Normalized null hypersurfaces in the Lorentz-Minkowski space satisfying $L_r x =U x +b$ Lorentz-Minkowski空间中满足L_r x =U x +b的归一化零超曲面
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-08-21 DOI: 10.5556/j.tkjm.54.2023.4851
Hans FOTSING TETSING, C. Atindogbe, Ferdinand Nkageu
{"title":"Normalized null hypersurfaces in the Lorentz-Minkowski space satisfying $L_r x =U x +b$","authors":"Hans FOTSING TETSING, C. Atindogbe, Ferdinand Nkageu","doi":"10.5556/j.tkjm.54.2023.4851","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.4851","url":null,"abstract":"In the present paper, we classify all normalized null hypersurfaces $x: (M,g,N)toR^{n+2}_1$ endowed with UCC-normalization with vanishing $1-$form $tau$, satisfying $L_r x =U x +b$ for some (field of) screen constant matrix $Uin R^{(n+2)times(n+2)}$ and vector$binR^{n+2}_{1}$, where $L_r$ is the linearized operator of the$(r+1)th-$mean curvature of the normalized null hypersurface for$r=0,...,n$. For $r=0$, $L_0=Delta^eta$ is nothing but the (pseudo-)Laplacian operator on $(M, g, N)$. We prove that the lightcone $Lambda_0^{n+1}$, lightcone cylinders $Lambda_0^{m+1}timesR^{n-m}$, $1leq mleq n-1$ and $(r+1)-$maximal Monge null hypersurfaces are the only UCC-normalized Monge null hypersurface with vanishing normalization $1-$form $tau$ satisfying the above equation. In case $U$ is the (field of) scalar matrix $ lambda I$, $lambdainR$ and hence is constant on the whole $M$, we show that the only normalized Monge null hypersurfaces $x: (M,g,N)toR^{n+2}_1$ satisfying $Delta^eta x =lambda x +b$, are open pieces of hyperplanes.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"40 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87209023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 1
Suberesolving codes Suberesolving代码
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-07-29 DOI: 10.5556/j.tkjm.54.2023.4635
Somayyeh Jangjooye Shaldehi
{"title":"Suberesolving codes","authors":"Somayyeh Jangjooye Shaldehi","doi":"10.5556/j.tkjm.54.2023.4635","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.4635","url":null,"abstract":"‎We show that any right continuing factor code with retract  0  into an irreducible shift of finite type is right eresolving‎, ‎and we give some sufficient conditions for a right eresolving almost everywhere code being right eresolving everywhere‎. ‎Suberesolving codes as a generalization of ersolving codes have been introduced and we determine some shift spaces which preserved by suberesolving codes‎. ‎Also‎, ‎we show that any bi-eresolving (resp‎. ‎bi-suberesolving) code on an irreducible shift of finite type (resp‎. ‎a synchronized system) is open (resp‎. ‎semi-open) and any right suberesolving code on a synchronized system is right continuing almost everywhere‎.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"113 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77250418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
On the signed strong total Roman domination number of graphs 关于有符号的强总罗马统治数图
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-07-29 DOI: 10.5556/j.tkjm.54.2023.3907
A. Mahmoodi, M. Atapour, S. Norouzian
{"title":"On the signed strong total Roman domination number of graphs","authors":"A. Mahmoodi, M. Atapour, S. Norouzian","doi":"10.5556/j.tkjm.54.2023.3907","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.3907","url":null,"abstract":"Let $G=(V,E)$ be a finite and simple graph of order $n$ and maximumdegree $Delta$. A signed strong total Roman dominating function ona graph $G$ is a function $f:V(G)rightarrow{-1, 1,2,ldots, lceilfrac{Delta}{2}rceil+1}$ satisfying the condition that (i) forevery vertex $v$ of $G$, $f(N(v))=sum_{uin N(v)}f(u)geq 1$, where$N(v)$ is the open neighborhood of $v$ and (ii) every vertex $v$ forwhich $f(v)=-1$ is adjacent to at least one vertex$w$ for which $f(w)geq 1+lceilfrac{1}{2}vert N(w)cap V_{-1}vertrceil$, where$V_{-1}={vin V: f(v)=-1}$.The minimum of thevalues $omega(f)=sum_{vin V}f(v)$, taken over all signed strongtotal Roman dominating functions $f$ of $G$, is called the signed strong totalRoman domination number of $G$ and is denoted by $gamma_{ssTR}(G)$.In this paper, we initiate signed strong total Roman domination number of a graph and giveseveral bounds for this parameter. Then, among other results, we determine the signed strong total Roman dominationnumber of special classes of graphs.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"85 1","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73035392","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
CR-submanifolds of SQ-Sasakian manifold sq - sasaki流形的cr -子流形
IF 0.6
Tamkang Journal of Mathematics Pub Date : 2022-07-29 DOI: 10.5556/j.tkjm.54.2023.4656
S. Yadav, S. Hui, Mohd Iqbal, Pradip Mandal, M. Aslam
{"title":"CR-submanifolds of SQ-Sasakian manifold","authors":"S. Yadav, S. Hui, Mohd Iqbal, Pradip Mandal, M. Aslam","doi":"10.5556/j.tkjm.54.2023.4656","DOIUrl":"https://doi.org/10.5556/j.tkjm.54.2023.4656","url":null,"abstract":"In this paper we discussed CR-submanifold of SQ-Sasakian manifold. Next, we considered Chaki pseudo parallel as well as Deszcz pseudo parallel CR-submanifold of SQ-Sasakian manifold. Further we studied almost Ricci soliton and almost Yamabe soliton with torse forming vector field on CR-subamnifold of SQ-Sasakian manifold using semi-symmetric metric connection.","PeriodicalId":45776,"journal":{"name":"Tamkang Journal of Mathematics","volume":"2 4","pages":""},"PeriodicalIF":0.6,"publicationDate":"2022-07-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72467106","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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