Pub Date : 2022-06-08DOI: 10.24193/subbmath.2022.2.06
Jerry R. Muir
"We consider the image of a linear-invariant family $mathcal{F}$ of normalized locally biholomorphic mappings defined in the Euclidean unit ball $B_n$ of $C^n$ under the extension operator $$Phi_{n,m,beta}[f](z,w) = mleft( f(z), [Jf(z)]^beta wmright), quad (z,w) in B_{n+m} subseteq C^n times C^m,$$ where $beta in C$, $Jf$ denotes the Jacobian determinant of $f$, and the branch of the power function taking $0$ to $1$ is used. When $beta=1/(n+1)$ and $m=1$, this is the Pfaltzgraff--Suffridge extension operator. In particular, we determine the order of the linear-invariant family on $B_{n+m}$ generated by the image in terms of the order of $mathcal{F}$, taking note that the resulting family has minimum order if and only if either $beta in (-1/m,1/(n+1)]$ and the family $mathcal{F}$ has minimum order or $beta=-1/m$. We will also see that order is preserved when generating a linear-invariant family from the family obtained by composing $mathcal{F}$ with a certain type of automorphism of $C^n$, leading to consequences for various extension operators including the modified Roper--Suffridge extension operator introduced by the author."
{"title":"Linear invariance and extension operators of Pfaltzgraff-Suffridge type","authors":"Jerry R. Muir","doi":"10.24193/subbmath.2022.2.06","DOIUrl":"https://doi.org/10.24193/subbmath.2022.2.06","url":null,"abstract":"\"We consider the image of a linear-invariant family $mathcal{F}$ of normalized locally biholomorphic mappings defined in the Euclidean unit ball $B_n$ of $C^n$ under the extension operator $$Phi_{n,m,beta}[f](z,w) = mleft( f(z), [Jf(z)]^beta wmright), quad (z,w) in B_{n+m} subseteq C^n times C^m,$$ where $beta in C$, $Jf$ denotes the Jacobian determinant of $f$, and the branch of the power function taking $0$ to $1$ is used. When $beta=1/(n+1)$ and $m=1$, this is the Pfaltzgraff--Suffridge extension operator. In particular, we determine the order of the linear-invariant family on $B_{n+m}$ generated by the image in terms of the order of $mathcal{F}$, taking note that the resulting family has minimum order if and only if either $beta in (-1/m,1/(n+1)]$ and the family $mathcal{F}$ has minimum order or $beta=-1/m$. We will also see that order is preserved when generating a linear-invariant family from the family obtained by composing $mathcal{F}$ with a certain type of automorphism of $C^n$, leading to consequences for various extension operators including the modified Roper--Suffridge extension operator introduced by the author.\"","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"13 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-06-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85110311","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}
Pub Date : 2022-05-03DOI: 10.24193/subbmath.2023.1.09
B. Ricceri
"Here is a sample of the results proved in this paper: Let $f:{bf R}to {bf R}$ be a continuous function, let $rho>0$ and let $omega:[0,rho[to [0,+infty[$ be a continuous increasing function such that $$limlimits_{xito rho^-}dsint_0^{xi}omega(x)dx=+infty.$$ Consider $C^0([0,1])times C^0([0,1])$ endowed with the norm $$|(alpha,beta)|=int_0^1|alpha(t)|dt+int_0^1|beta(t)|dt.$$ Then, the following assertions are equivalent: noindent $(a)$ the restriction of $f$ to $left [-{{sqrt{rho}}over {2}},{{sqrt{rho}}over {2}} right ]$ is not constant; noindent $(b)$ for every convex set $Ssubseteq C^0([0,1])times C^0([0,1])$ dense in $C^0([0,1])times C^0([0,1])$, there exists $(alpha,beta)in S$ such that the problem $$left{begin{array}{l} -omegaleft(displaystyleint_0^1|u'(t)|^2dtright)u'' =beta(t)f(u)+alpha(t) mbox{ in } [0,1] u(0)=u(1)=0 displaystyleint_0^1|u'(t)|^2dt
{"title":"Multiplicity theorems involving functions with non-convex range","authors":"B. Ricceri","doi":"10.24193/subbmath.2023.1.09","DOIUrl":"https://doi.org/10.24193/subbmath.2023.1.09","url":null,"abstract":"\"Here is a sample of the results proved in this paper: Let $f:{bf R}to {bf R}$ be a continuous function, let $rho>0$ and let $omega:[0,rho[to [0,+infty[$ be a continuous increasing function such that $$limlimits_{xito rho^-}dsint_0^{xi}omega(x)dx=+infty.$$ Consider $C^0([0,1])times C^0([0,1])$ endowed with the norm $$|(alpha,beta)|=int_0^1|alpha(t)|dt+int_0^1|beta(t)|dt.$$ Then, the following assertions are equivalent: noindent $(a)$ the restriction of $f$ to $left [-{{sqrt{rho}}over {2}},{{sqrt{rho}}over {2}} right ]$ is not constant; noindent $(b)$ for every convex set $Ssubseteq C^0([0,1])times C^0([0,1])$ dense in $C^0([0,1])times C^0([0,1])$, there exists $(alpha,beta)in S$ such that the problem $$left{begin{array}{l} -omegaleft(displaystyleint_0^1|u'(t)|^2dtright)u'' =beta(t)f(u)+alpha(t) mbox{ in } [0,1] u(0)=u(1)=0 displaystyleint_0^1|u'(t)|^2dt<rho end{array}right.$$ has at least two classical solutions.\"","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"62 27","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72511076","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}
Pub Date : 2022-04-01DOI: 10.2478/subboec-2022-0001
Yvesa Jusaj, Besnik Fetai
Abstract This paper investigates the relationship between female education and economic growth in Western Balkan countries during the period 2000-2019. The motive behind choosing Western Balkan countries was because there is insufficient research that has been made in this field of study; hence, this research assists to expand the issue of this topic. By using GDP as dependent variable, the paper addresses the question whether female education generates or not economic growth. The techniques applied for this study are OLS, fixed and random effects, and Hausman-Taylor model IVs. The findings show a positive relationship between GDP per capita, female labor participation, school enrollment primary, and literacy rate. On the other hand, there exists a negative relationship with fertility rate, while the school enrollment tertiary is statistically insignificant. This paper brings evidence that female education generates more economic growth in Western Balkan countries. Therefore, the Government of the Western Balkans should take into consideration to invest more on education of the woman in those countries. These in turn will lead to higher economic growth.
{"title":"Does Female Education Generate Economic Growth? An Empirical Analysis of Western Balkan Countries","authors":"Yvesa Jusaj, Besnik Fetai","doi":"10.2478/subboec-2022-0001","DOIUrl":"https://doi.org/10.2478/subboec-2022-0001","url":null,"abstract":"Abstract This paper investigates the relationship between female education and economic growth in Western Balkan countries during the period 2000-2019. The motive behind choosing Western Balkan countries was because there is insufficient research that has been made in this field of study; hence, this research assists to expand the issue of this topic. By using GDP as dependent variable, the paper addresses the question whether female education generates or not economic growth. The techniques applied for this study are OLS, fixed and random effects, and Hausman-Taylor model IVs. The findings show a positive relationship between GDP per capita, female labor participation, school enrollment primary, and literacy rate. On the other hand, there exists a negative relationship with fertility rate, while the school enrollment tertiary is statistically insignificant. This paper brings evidence that female education generates more economic growth in Western Balkan countries. Therefore, the Government of the Western Balkans should take into consideration to invest more on education of the woman in those countries. These in turn will lead to higher economic growth.","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"19 1","pages":"1 - 10"},"PeriodicalIF":0.0,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80456906","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}
Pub Date : 2022-04-01DOI: 10.2478/subboec-2022-0004
M. Oberholzer, Matthew Olubayo Omotoso, D. Schutte, Pieter Buys
Abstract Within the context that the adoption of International Financial Reporting Standards (IFRS) can be linked to institutional isomorphism, the purpose of the study was to determine how successful IFRS-adopted African countries are to convert governance and economic factors into foreign direct investment (FDI) and foreign portfolio investment (FPI). Data envelopment analysis (DEA) was used to develop two models to calculate the technical efficiency (TE) for 16 African countries that adopted IFRS (2014-2019). The first model considered how multiple economic factors as input variables are converted into FDI and FPI, while similarly, the second model considered governance factors as input variables.
{"title":"The Relative Success of IFRS Adopted African Countries to Attract Foreign Investment","authors":"M. Oberholzer, Matthew Olubayo Omotoso, D. Schutte, Pieter Buys","doi":"10.2478/subboec-2022-0004","DOIUrl":"https://doi.org/10.2478/subboec-2022-0004","url":null,"abstract":"Abstract Within the context that the adoption of International Financial Reporting Standards (IFRS) can be linked to institutional isomorphism, the purpose of the study was to determine how successful IFRS-adopted African countries are to convert governance and economic factors into foreign direct investment (FDI) and foreign portfolio investment (FPI). Data envelopment analysis (DEA) was used to develop two models to calculate the technical efficiency (TE) for 16 African countries that adopted IFRS (2014-2019). The first model considered how multiple economic factors as input variables are converted into FDI and FPI, while similarly, the second model considered governance factors as input variables.","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"57 1","pages":"44 - 62"},"PeriodicalIF":0.0,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84795264","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}
Pub Date : 2022-04-01DOI: 10.2478/subboec-2022-0005
J. Olowookere, W. Olanipekun, Gbenro Matthew Sokunbi, T. Aderemi
Abstract The contributions of human capital development in achieving the sustainable development cannot be overemphasized in any economy, this is because investment in education and health has been argued as the strategic impetus for improving the quality of human resources. Against this backdrop, this study investigates the impact of human capital development on the sustainable development goal one (1) – poverty reduction. The study utilizes the Nigerian data combining Johansen Cointegration test, Granger causality test and Fully Modified Least Squares to establish how public investments in both education and health affect poverty reduction in the country between 1981 and 2019. Originating from the findings of this study, both government expenditure on health and capital formation Granger caused poverty reduction in Nigeria. This is a vital signal that human capital development in the form of investment in health of human resources is an important condition for the achievement of the sustainable development goal one (1) – poverty eradication in Nigeria. Similarly, all the selected components of human capital development have positive contributions to poverty reduction in Nigeria. However, the contributions of health expenditures and capital formation are statistically significant. This implies that health expenditures and capital formation have a trickle-down effect on poverty reduction in Nigeria. Therefore, this study recommends the following: any time the Nigerian policymakers want to achieve the sustainable development goal one (1) – poverty reduction, the Nigerian budgetary allocations to education and health sectors should be in tandem with the global benchmark; this would ensure material and human resources that could drive the country towards the sustainable development. The enhancement of educational and health facilities by the policymakers would also bring about improvement in the living standard of the Nigerians.
{"title":"Human Capital Development and Sustainable Development: Evidence from Nigeria","authors":"J. Olowookere, W. Olanipekun, Gbenro Matthew Sokunbi, T. Aderemi","doi":"10.2478/subboec-2022-0005","DOIUrl":"https://doi.org/10.2478/subboec-2022-0005","url":null,"abstract":"Abstract The contributions of human capital development in achieving the sustainable development cannot be overemphasized in any economy, this is because investment in education and health has been argued as the strategic impetus for improving the quality of human resources. Against this backdrop, this study investigates the impact of human capital development on the sustainable development goal one (1) – poverty reduction. The study utilizes the Nigerian data combining Johansen Cointegration test, Granger causality test and Fully Modified Least Squares to establish how public investments in both education and health affect poverty reduction in the country between 1981 and 2019. Originating from the findings of this study, both government expenditure on health and capital formation Granger caused poverty reduction in Nigeria. This is a vital signal that human capital development in the form of investment in health of human resources is an important condition for the achievement of the sustainable development goal one (1) – poverty eradication in Nigeria. Similarly, all the selected components of human capital development have positive contributions to poverty reduction in Nigeria. However, the contributions of health expenditures and capital formation are statistically significant. This implies that health expenditures and capital formation have a trickle-down effect on poverty reduction in Nigeria. Therefore, this study recommends the following: any time the Nigerian policymakers want to achieve the sustainable development goal one (1) – poverty reduction, the Nigerian budgetary allocations to education and health sectors should be in tandem with the global benchmark; this would ensure material and human resources that could drive the country towards the sustainable development. The enhancement of educational and health facilities by the policymakers would also bring about improvement in the living standard of the Nigerians.","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"96 1","pages":"63 - 76"},"PeriodicalIF":0.0,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89906642","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}
Pub Date : 2022-04-01DOI: 10.2478/subboec-2022-0003
Zahia Bouzida, Nadir Malek, S. Ghomari
Abstract The paper aims to synthesize the lessons learned from the analysis of the ISO 9001 quality management system standard. The objective is twofold: first, to understand the role of human capital in the conduct and success of an innovation project within a company, and secondly, to explain the simultaneous effect of this dynamic on the emergence of innovative behaviors. An exploratory study is established with the personnel of the first ISO certified company in Algeria and the proposed hypotheses are tested by the partial least squares structural equation modeling (PLS-sem) method. Analysis of the results show that by acting on certain mechanisms, these standards can be assimilated to a catalog of data that can be utilized to encourage and promote the construction and development of skills and competencies. The findings allow us to better understand the nature of the relationship that may exist between skills management and the quality approach.
{"title":"Capitalization of Human Skills and Competencies – An Exploratory Model","authors":"Zahia Bouzida, Nadir Malek, S. Ghomari","doi":"10.2478/subboec-2022-0003","DOIUrl":"https://doi.org/10.2478/subboec-2022-0003","url":null,"abstract":"Abstract The paper aims to synthesize the lessons learned from the analysis of the ISO 9001 quality management system standard. The objective is twofold: first, to understand the role of human capital in the conduct and success of an innovation project within a company, and secondly, to explain the simultaneous effect of this dynamic on the emergence of innovative behaviors. An exploratory study is established with the personnel of the first ISO certified company in Algeria and the proposed hypotheses are tested by the partial least squares structural equation modeling (PLS-sem) method. Analysis of the results show that by acting on certain mechanisms, these standards can be assimilated to a catalog of data that can be utilized to encourage and promote the construction and development of skills and competencies. The findings allow us to better understand the nature of the relationship that may exist between skills management and the quality approach.","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"145 1","pages":"27 - 43"},"PeriodicalIF":0.0,"publicationDate":"2022-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73147242","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}
Pub Date : 2022-03-10DOI: 10.24193/subbmath.2022.1.13
Abita Rahmoune, B. Benabderrahmane
This report deals with a blow-up of the solutions to a class of semilinear parabolic equations with variable exponents nonlinearities. Under some appropriate assumptions on the given data, a more general lower bound for a blow-up time is obtained if the solutions blow up. This result extends the recent results given by Baghaei Khadijeh et al. cite{Baghaei}, which ensures the lower bounds for the blow-up time of solutions with initial data $varphileft( 0right) =int_{Omega }u_{0}{}^{k}dx$, $k$ = constant.
本文讨论了一类非线性变指数半线性抛物型方程解的爆破问题。在给定数据的适当假设下,如果解爆破,则得到爆破时间的一个更一般的下界。该结果推广了Baghaei Khadijeh et al. cite{Baghaei}最近给出的结果,该结果保证了初始数据$varphileft( 0right) =int_{Omega }u_{0}{}^{k}dx$, $k$ =常数时解的爆破时间下界。
{"title":"Bounds for blow-up time in a semilinear parabolicproblem with variable exponents","authors":"Abita Rahmoune, B. Benabderrahmane","doi":"10.24193/subbmath.2022.1.13","DOIUrl":"https://doi.org/10.24193/subbmath.2022.1.13","url":null,"abstract":"This report deals with a blow-up of the solutions to a class of semilinear parabolic equations with variable exponents nonlinearities. Under some appropriate assumptions on the given data, a more general lower bound for a blow-up time is obtained if the solutions blow up. This result extends the recent results given by Baghaei Khadijeh et al. cite{Baghaei}, which ensures the lower bounds for the blow-up time of solutions with initial data $varphileft( 0right) =int_{Omega }u_{0}{}^{k}dx$, $k$ = constant.","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75065658","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}
Pub Date : 2022-03-10DOI: 10.24193/subbmath.2022.1.06
N. T. Vinh, N. T. Thuong
"In this paper, we propose a relaxed version of the gradient projection method for strongly monotone variational inequalities de ned on a level set of a (possibly non-di erentiable) convex function. Our algorithm can be implemented easily since it computes on every iteration one projection onto some half-space containing the feasible set and only one value of the underlying mapping. Under mild and standard conditions we establish the strong convergence of the proposed algorithm. Numerical results and comparisons for the image deblurring problem show that our method can outperform related algorithms in the literature."
{"title":"A relaxed version of the gradient projection method for variational inequalities with applications","authors":"N. T. Vinh, N. T. Thuong","doi":"10.24193/subbmath.2022.1.06","DOIUrl":"https://doi.org/10.24193/subbmath.2022.1.06","url":null,"abstract":"\"In this paper, we propose a relaxed version of the gradient projection method for strongly monotone variational inequalities de ned on a level set of a (possibly non-di erentiable) convex function. Our algorithm can be implemented easily since it computes on every iteration one projection onto some half-space containing the feasible set and only one value of the underlying mapping. Under mild and standard conditions we establish the strong convergence of the proposed algorithm. Numerical results and comparisons for the image deblurring problem show that our method can outperform related algorithms in the literature.\"","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"27 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83997915","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}
Pub Date : 2022-03-10DOI: 10.24193/subbmath.2022.1.11
H. Budak, M. Ali, A. Kashuri
"In this paper, we rstly summarize some properties of the family F and F-convex functions which are de ned by B. Samet. Utilizing generalized fractional integrals new Hermite-Hadamard type inequalities for F-convex functions have been provided. Some results given earlier works are also as special cases of our results."
{"title":"Hermite-Hadamard type inequalities for F-convex functions involving generalized fractional integrals","authors":"H. Budak, M. Ali, A. Kashuri","doi":"10.24193/subbmath.2022.1.11","DOIUrl":"https://doi.org/10.24193/subbmath.2022.1.11","url":null,"abstract":"\"In this paper, we rstly summarize some properties of the family F and F-convex functions which are de ned by B. Samet. Utilizing generalized fractional integrals new Hermite-Hadamard type inequalities for F-convex functions have been provided. Some results given earlier works are also as special cases of our results.\"","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"79 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82586129","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}
Pub Date : 2022-03-10DOI: 10.24193/subbmath.2022.1.10
T. Precupanu
In the previous paper, we have defined together with I. Ionicu{a} the heights of a nontrivial triangle with respect to Birkhoff orthogonality in a real smooth space $X$, $mbox{dim}, Xgeq 2.$ In the present paper, we remark that, generally, the area of a nontrivial triangle in $X$ has not the same value for different heights of the triangle. The purpose of this paper is to characterize the norm of $X$ if this space has the property that the area of any triangle is well defined (independent of considered height). In this line we give five equivalent properties using the directional derivative of the norm. If $X$ is strictly convex and $mbox{dim} Xgeq 3$, then each of these five properties characterizes the hilbertian norms (generated by inner products).
{"title":"Characterizations of hilbertian norms involving the areas of triangles in a smooth space","authors":"T. Precupanu","doi":"10.24193/subbmath.2022.1.10","DOIUrl":"https://doi.org/10.24193/subbmath.2022.1.10","url":null,"abstract":"In the previous paper, we have defined together with I. Ionicu{a} the heights of a nontrivial triangle with respect to Birkhoff orthogonality in a real smooth space $X$, $mbox{dim}, Xgeq 2.$ In the present paper, we remark that, generally, the area of a nontrivial triangle in $X$ has not the same value for different heights of the triangle. The purpose of this paper is to characterize the norm of $X$ if this space has the property that the area of any triangle is well defined (independent of considered height). In this line we give five equivalent properties using the directional derivative of the norm. If $X$ is strictly convex and $mbox{dim} Xgeq 3$, then each of these five properties characterizes the hilbertian norms (generated by inner products).","PeriodicalId":30022,"journal":{"name":"Studia Universitatis BabesBolyai Geologia","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2022-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84481197","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}