Some characterizations of three-dimensional trans-Sasakian manifolds admitting η- Ricci solitons and trans-Sasakian manifolds as Kagan subprojective space

UDC 514.7 The object of the present paper is to study three-dimensional trans-Sasakian manifolds admitting $\eta$-Ricci soliton. Actually, we study such manifolds whose Ricci tensor satisfy some special conditions like cyclic parallelity, Ricci semisymmetry, $\phi$-Ricci semisymmetry, after reviewin...

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Main Authors: Sarkar, A., Sil, A., Paul, A. K., Саркар, А., Сіл, А., Пауль, А. К.
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Ukrains’kyi Matematychnyi Zhurnal
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author Sarkar, A.
Sil, A.
Paul, A. K.
Саркар, А.
Сіл, А.
Пауль, А. К.
author_facet Sarkar, A.
Sil, A.
Paul, A. K.
Саркар, А.
Сіл, А.
Пауль, А. К.
author_sort Sarkar, A.
baseUrl_str https://umj.imath.kiev.ua/index.php/umj/oai
collection OJS
datestamp_date 2020-05-26T09:20:33Z
description UDC 514.7 The object of the present paper is to study three-dimensional trans-Sasakian manifolds admitting $\eta$-Ricci soliton. Actually, we study such manifolds whose Ricci tensor satisfy some special conditions like cyclic parallelity, Ricci semisymmetry, $\phi$-Ricci semisymmetry, after reviewing the properties of second order parallel tensors on such manifolds. We determine the form of Riemann curvature tensor of trans-Sasakian manifolds of dimension greater than three as Kagan subprojective spaces. We also give some classification results of trans-Sasakian manifolds of dimension greater than three as Kagan subprojective spaces.
doi_str_mv 10.37863/umzh.v72i3.6047
first_indexed 2026-03-24T03:25:50Z
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fulltext UDC 514.7 A. Sarkar, A. Sil, A. K. Paul (Univ. Kalyani, West Bengal, India) SOME CHARACTERIZATIONS OF THREE-DIMENSIONAL TRANS-SASAKIAN MANIFOLDS ADMITTING \bfiteta -RICCI SOLITONS AND TRANS-SASAKIAN MANIFOLDS AS KAGAN SUBPROJECTIVE SPACES ДЕЯКI ХАРАКТЕРИСТИКИ ТРИВИМIРНИХ ТРАНС-МНОГОВИДIВ САСАКЯНА, ЩО ДОПУСКАЮТЬ \bfiteta -СОЛIТОНИ РIЧЧI, ТА ТРАНС-МНОГОВИДИ САСАКЯНА ЯК СУБПРОЕКТИВНI ПРОСТОРИ КАГАНА The object of the present paper is to study three-dimensional trans-Sasakian manifolds admitting \eta -Ricci soliton. Actually, we study such manifolds whose Ricci tensor satisfy some special conditions like cyclic parallelity, Ricci semisymmetry, \phi -Ricci semisymmetry, after reviewing the properties of second order parallel tensors on such manifolds. We determine the form of Riemann curvature tensor of trans-Sasakian manifolds of dimension greater than three as Kagan subprojective spaces. We also give some classification results of trans-Sasakian manifolds of dimension greater than three as Kagan subprojective spaces. Вивчаються тривимiрнi транс-многовиди Сасакяна, якi допускають \eta -солiтони Рiччi. Власне, пiсля огляду власти- востей паралельних тензорiв другого порядку на таких многовидах ми вивчаємо многовиди, тензор Рiччi яких задовольняє деякi спецiальнi умови, такi як циклiчна паралельнiсть, напiвсиметрiя Рiччi, \phi -напiвсиметрiя Рiччi. Визначено форму тензора кривини Рiмана для транс-многовидiв Сасакяна, розмiрнiсть яких бiльша нiж 3, як суб- проективних просторiв Кагана. Також наведено деякi класифiкацiйнi результати для транс-многовидiв Сасакяна, розмiрнiсть яких бiльша нiж 3, як субпроективних просторiв Кагана. 1. Introduction. In [18], R. S. Hamilton introduced the revolutionary concept of Ricci flow on surfaces. The concepts of Ricci flow in physics was introduced by Friedan [14] almost around in the same time but with different motivations. Now a days such geometric flows have become popular, largely, because of Perelman’s [22] work which lead to the proof of well known Poincaré conjecture. A Ricci soliton is a special solution of Ricci flow. This is considered as a natural generalization of Einstein metric and is defined on a Riemannian manifold (M, g) by (\$V g)(X,Y ) + 2S(X,Y ) + 2\lambda g(X,Y ) = 0, (1.1) where \$V denotes the Lie derivative operator along a complete vector field V. V is known as potential vector field. \lambda is a constant, called soliton constant. S is the Ricci tensor and g is the metric. X, Y are the arbitrary vector fields on M. The Ricci soliton is said to be shrinking, steady or expanding as \lambda is negative, zero or positive, respectively [7]. The study of Ricci solitons on contact manifolds was initiated by R. Sharma [24]. Later several authors have studied Ricci soliton on almost contact manifolds. For example, we may refer the papers [12, 15, 16, 27]. In [5], it has been proved that a real hypersurface in a non-flat complex space form does not admit a Ricci soliton with \xi as soliton vector field and then the author adopted the notion of \eta -Ricci soliton. The \eta -Ricci soliton (g, \xi , \lambda , \mu ) on a Riemannian manifold is defined by \$\xi g + 2S + 2\lambda - 2\mu n\otimes n = 0, where \xi is the Reeb vector field, \mu is a constant and the other objects are as described in equa- tion (1.1). For details see also [2, 6, 8, 23]. Since 1923 [13], second order parallel tensors are studied c\bigcirc A. SARKAR, A. SIL, A. K. PAUL, 2020 ISSN 1027-3190. Укр. мат. журн., 2020, т. 72, № 3 427 428 A. SARKAR, A. SIL, A. K. PAUL by several authors [20]. Second order parallel tensors were studied in the frame work of contact manifolds by R. Sharma [25]. If geodesics are represented by n - 2 homogeneous linear equations for a suitable coordinate system in an affine space An, then An is called a subprojective space by B. Kagan [19]. T. Adati [1] have studied such spaces intensively and proved that Kagan subprojective spaces are conformally flat [1, p. 160]. In this paper, we would like to find form of Riemann curvature tensors of trans- Sasakian manifolds of dimension greater than three as Kagan subprojective spaces. We give some classification results of such spaces. 2. Preliminaries. Let M be a differentiable manifold of dimension 2n + 1. M is said to have almost contact structure [3] if there is a (1,1) tensor field \phi , a vector field \xi and a 1-form \eta on M such that \phi 2X = - X + \eta (X)\xi , \eta (\xi ) = 1, where X \in \chi (M), the set of all differentiable vector fields on M. On such manifolds it can be also proved that \phi \xi = 0, \eta (\phi X) = 0, g(X,\phi Y ) = - g(\phi X, Y ), g(X, \xi ) = \eta (X) for X,Y \in \chi (M). An almost contact structure is called almost contact metric structure if there exists a Riemannian metric g on M satisfying g(\phi X, \phi Y ) = g(X,Y ) - \eta (X)\eta (Y ). The (0,2) tensor field \Phi defined by \Phi (X,Y ) = g(X,\phi Y ) is known as fundamental 2-form of the manifold. If \Phi is closed, an almost contact metric structure reduces to contact metric structure [3]. An almost contact metric structure (\phi , \xi , \eta , g) on a differentiable manifold M is called a trans-Sasakian structure [21] if (M \times R, J,G) belongs to the class W4 in the Gray – Hervella classification [17]. Here J is the almost complex structure on M\times R defined by J \biggl( X, f d dt \biggr) = \biggl( \phi X - f\xi , \eta (X) d dt \biggr) , for all vector fields X on M and smooth functions f on M \times R and G is the product metric on M \times R. This fact may be formulated by the following equation [4]: (\nabla X\phi )Y = \alpha \bigl( g(X,Y )\xi - \eta (Y )X \bigr) + \beta \bigl( g(\phi X, Y )\xi - \eta (Y )\phi X \bigr) , where \alpha and \beta are smooth functions on M. The above formula implies \nabla X\xi = \beta (X - \eta (X)\xi ) - \alpha \phi X, (2.1) (\nabla X\eta )Y = - \alpha g(\phi X, Y ) + \beta g(\phi X, \phi Y ). (2.2) The Ricci tensor [11] of a three-dimensional trans-Sasakian manifold is given by S(X,Y ) = \Bigl( r 2 + \xi \beta - \bigl( \alpha 2 - \beta 2 \bigr) \Bigr) g(X,Y ) - \Bigl( r 2 + \xi \beta - 3 \bigl( \alpha 2 - \beta 2 \bigr) \Bigr) \eta (X)\eta (Y ) - - \bigl( Y \beta + (\phi Y )\alpha \bigr) \eta (X) - \bigl( X\beta + (\phi X)\alpha \bigr) \eta (Y ), (2.3) where r is the scalar curvature of the manifold. Again from [9], we known that the Riemann curvature of a three-dimensional trans-Sasakian manifold is given by ISSN 1027-3190. Укр. мат. журн., 2020, т. 72, № 3 SOME CHARACTERIZATIONS OF THREE-DIMENSIONAL TRANS-SASAKIAN MANIFOLDS . . . 429 R(X,Y )Z = \Bigl( r 2 + 2\xi \beta - 2 \bigl( \alpha 2 - \beta 2 \bigr) \Bigr) \bigl( g(Y,Z)X - g(X,Z)Y \bigr) - - g(Y, Z) \Bigl[ \Bigl( r 2 + \xi \beta - 3 \bigl( \alpha 2 - \beta 2 \bigr) \Bigr) \eta (X)\xi - \eta (X)(\phi \mathrm{g}\mathrm{r}\mathrm{a}\mathrm{d}\alpha - \mathrm{g}\mathrm{r}\mathrm{a}\mathrm{d}\beta )+ + (X\beta + (\phi X)\alpha )\xi \Bigr] + g(X,Z) \Bigl[ \Bigl( r 2 + \xi \beta - 3 \bigl( \alpha 2 - \beta 2 \bigr) \Bigr) \eta (Y )\xi - \eta (Y )(\phi \mathrm{g}\mathrm{r}\mathrm{a}\mathrm{d}\alpha - \mathrm{g}\mathrm{r}\mathrm{a}\mathrm{d}\beta )+ + (Y \beta + (\phi Y )\alpha )\xi \Bigr] - \Bigl[ \bigl( Z\beta + (\phi Z)\alpha \bigr) \eta (Y ) + (Y \beta + (\phi Y )\alpha )\eta (Z) + + \Bigl( r 2 + \xi \beta - 3 \bigl( \alpha 2 - \beta 2 \bigr) \Bigr) \eta (Y )\eta (Z) \Bigr] X + \Bigl[ (Z\beta + (\phi Z)\alpha )\eta (X) + + \bigl( X\beta + (\phi X)\alpha \bigr) \eta (Z) + \Bigl( r 2 + \xi \beta - 3 \bigl( \alpha 2 - \beta 2 \bigr) \Bigr) \eta (X)\eta (Z) \Bigr] Y. (2.4) Again 2\alpha \beta + \xi \alpha = 0. 3. Existence criteria of \bfiteta -Ricci soliton on three-dimensional trans-Sasakian manifolds. Theorem 3.1. A three-dimensional trans-Sasakian manifold with constant \xi -sectional curvature admits \eta -Ricci soliton if and only if \$\xi g + 2S + 2\mu n\otimes n is parallel. Theorem 3.2. A three-dimensional proper trans-Sasakian manifold with cyclic parallel Ricci tensor does not admit \eta -Ricci soliton. It reduces to Einstein manifold. Proof. Let (M, g, \xi , \lambda , \mu ) be a three-dimensional trans-Sasakian \eta -Ricci soliton. Then we have (\$\xi g)(X,Y ) + 2S(X,Y ) + 2\lambda g(X,Y ) + 2\mu \eta (X)\eta (Y ) = 0. Expressing the Lie derivative in terms of covariant derivative and using (2.1), we obtain S(X,Y ) = - 2\lambda + \beta 2 g(X,Y ) + 2\mu - \beta 2 \eta (X)\eta (Y ). (3.1) In [12], it was proved that if T is a symmetric parallel tensor on a trans-Sasakian manifold of dimension three with non-zero \xi -sectional curvature, then T (X,Y ) = T (\xi , \xi )g(X,Y ). We see that (\$\xi g)(X,Y ) + 2S(X,Y ) + 2\mu \eta (X)\eta (Y ) is a symmetric (0, 2) tensor. Hence, by using its property, we obtain Theorem 3.1. Consider the manifold has cyclic parallel Ricci tensor [9]. By virtue of (3.1) and (2.3), after simplification we have S = - 2(\lambda + \beta ) 2 g. Theorem 3.2 is proved. 4. Ricci semisymmetric three-dimensional trans-Sasakian manifold admitting \bfiteta -Ricci soli- ton. Theorem 4.1. If a three-dimensional trans-Sasakian manifold of type (\alpha , \beta ), where \alpha \not = \pm \beta and \beta = \mathrm{c}\mathrm{o}\mathrm{n}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{n}\mathrm{t}, admitting \eta -Ricci soliton is Ricci semisymmetric, then \mu = \beta 2 . Corollary 4.1. A Ricci semisymmetric three-dimensional \alpha -Sasakian manifold does not admit proper \eta -Ricci soliton. ISSN 1027-3190. Укр. мат. журн., 2020, т. 72, № 3 430 A. SARKAR, A. SIL, A. K. PAUL Proof. It is well known that a Riemannian manifold is called Ricci semisymmetric if (R(X,Y )S)(U, V ) = 0. The above condition implies S \bigl( R(X,Y )U, V \bigr) + S \bigl( U,R(X,Y )V =) = 0. Putting Y = V = \xi , we have S \bigl( R(X, \xi )U, \xi \bigr) + S \bigl( U,R(X, \xi )\xi \bigr) = 0. Using (2.4) in the above equation, after straight forward computation we have \mu = \beta 2 , provided \alpha \not = \pm \beta . So, we have Theorem 4.1 for \alpha -Sasakian case \alpha = \mathrm{c}\mathrm{o}\mathrm{n}\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{n}\mathrm{t} and \beta = 0. Thus we have Corollary 4.1. 5. \bfitphi -Ricci symmetric three-dimensional trans-Sasakian manifold admitting \bfiteta -Ricci soliton. The notion of \phi -Ricci symmetry was given by the first author in [10]. An almost contact manifold is called \phi -Ricci symmetric if the Ricci operator Q satisfies \phi 2(\nabla WQ)X = 0. The manifold is called locally \phi -Ricci symmetric if X and W are orthogonal to \xi . Theorem 5.1. A three-dimensional trans-Sasakian manifold admitting \eta -Ricci soliton is \phi -Ricci symmetric if and only if \mu = \beta 2 . Proof. By virtue of (3.1) we obtain QX = - 2\lambda + \beta 2 X + 2\mu - \beta 2 \eta (X)\xi . Hence, \phi 2(\nabla WQ)X = \alpha \biggl( \beta 2 - \mu \biggr) \eta (X)\phi 2(\phi W ) + \beta \biggl( \mu - \beta 2 \biggr) \phi 2W. The above equation proves Theorem 5.1. 6. Form of Riemann curvature tensors of trans-Sasakian manifolds of dimension greater than three as Kagan subprojective spaces. Riemann curvature tensors for three-dimensional trans- Sasakian manifolds have been deduced in the paper [11]. In this section, we like to deduce the form of Riemann curvature tensors of trans-Sasakian manifolds of dimension greater than three as Kagan subprojective spaces [19]. Theorem 6.1. The form of Riemann curvature tensor of a trans-Sasakian manifold of dimension greater than three as Kagan subprojective space is given by R(X,Y )Z = \biggl( r 2m(2m - 1) - 2 2m - 1 \Bigl( r 2m (\alpha 2 - \beta 2) \Bigr) \biggr) \bigl( g(Y, Z)X - g(X,Z)Y \bigr) + + 1 2m - 1 \Bigl( r 2m + (2m+ 1)(\alpha 2 - \beta 2) \Bigr) \bigl( \eta (Y )\eta (Z)X - \eta (X)\eta (Z)Y \bigr) . Theorem 6.2. A trans-Sasakian manifold of dimension greater than three as Kagan subprojec- tive space is Einstein manifold. Hence, it does not admit Ricci soliton and \eta -Ricci soliton. ISSN 1027-3190. Укр. мат. журн., 2020, т. 72, № 3 SOME CHARACTERIZATIONS OF THREE-DIMENSIONAL TRANS-SASAKIAN MANIFOLDS . . . 431 Proof. T. Adati [1] have proved that Kagan subprojective spaces are conformally flat. We know that the Weyl conformal curvature tensor C of a (2m + 1)-dimensional (m > 1) manifold is given by C(X,Y )Z = R(X,Y )Z - 1 2m - 1 \Bigl[ g(Y, Z)QX - g(X,Z)QY + S(Y,Z)X - S(X,Z)Y \Bigr] + + r 2m(2m - 1) \bigl[ g(Y,Z)X - g(X,Z)Y \bigr] , where S is Ricci tensor and Q is Ricci operator. Since Kagan subprojective spaces are conformally flat, we get R(X,Y )Z = 1 2m - 1 \Bigl[ g(Y,Z)QX - g(X,Z)QY + S(Y,Z)X - S(X,Z)Y \Bigr] - - r 2m(2m - 1) \Bigl[ g(Y,Z)X - g(X,Z)Y \Bigr] . From the above equation, we find S and Q and obtain the results. 7. Some classification results of a trans-Sasakian manifold of dimension greater than three as Kagan subprojective space. Definition 7.1. A Riemannian manifold is called locally \phi -symmetric [26] if \phi 2(\nabla WR)(X,Y )Z = 0, for X,Y, Z orthogonal to \xi . Theorem 7.1. A trans-Sasakian manifold of dimension greater than three as Kagan subprojec- tive space is locally \phi -symmetric if and only if dr 2m = 4(\alpha d\alpha - \beta d\beta ). Theorem 7.2. If the structure functions \alpha and \beta of a trans-Sasakian manifold of dimension greater than three as Kagan subprojective space are same, then the manifold is locally \phi -symmetric if and only if the scalar curvature of the manifold is constant. Theorem 7.3. If the structure functions \alpha and \beta of a trans-Sasakian manifold of dimension greater than three as Kagan subprojective space are constants, then the manifold is locally \phi - symmetric. Proof. By using Theorem 6.1, we get \phi 2(\nabla WR)(X,Y )Z = = \biggl( dr 2m(2m - 1) - 2 2m - 1 \biggl( dr 2m + 2 \bigl( \alpha d\alpha - \beta d\beta ) \biggr) \biggr) \Bigl( g(X,Z)Y - g(Y, Z)X \Bigr) , (7.1) for X, Y, Z orthogonal to \xi . Let us consider the following cases: Case 1. Consider \alpha and \beta as arbitrary functions: Subcase 1.1: Let \alpha \not = \beta . In that case we get Theorem 7.1 from (7.1). Subcase 1.2: Let \alpha and \beta are equal functions. In that case \alpha d\alpha - \beta d\beta = 0. So, we obtain Theorem 7.2 from (7.1). Case 2. Let \alpha and \beta are constants. In that case, deducing S from R, we have Theorem 7.3. ISSN 1027-3190. Укр. мат. журн., 2020, т. 72, № 3 432 A. SARKAR, A. SIL, A. K. PAUL References 1. T. Adati, On subprojective space I, Tohoku Math. J., 3, 159 – 173 (1951). 2. A. M. Blaga, \eta -Ricci solitons on Lorentzian para-Sasakian manifolds, Filomat, 30, 489 – 496 (2016). 3. D. E. Blair, Riemannian geometry of contact and symplectic manifolds, Progr. Math., 203, (2002). 4. D. E. Blair, J. A. Oubina, Conformal and related changes of metric on the product of two almost contact metric manifolds, Publ. Math., 34, 199 – 207 (1990). 5. J. T. Cho, M. Kimura, Ricci solitons and real hypersurfaces in a complex space form, Tohoku Math. J., 61, 205 – 212 (2009). 6. C. Calin, C. Crasmareanu, \eta -Ricci solitons on Hopf hypersurfaces in complex space forms, arxiv math. DG. 7. B. Chow, D. Knopf, The Ricci flow, An introduction, Math. Surveys and Monogr., 110 (2004). 8. M. Crasmareanu, Parallel tensor and Ricci solitons on N(K)-quasi-Einstein manifolds, Indian J. Pure and Appl. Math., 43, 359 – 369 (2012). 9. U. C. De, A. Sarkar, On three-dimensional trans-Sasakian manifolds, Extracta Math., 23, 247 – 255 (2008). 10. U. C. De, A. Sarkar, On \phi -Ricci symmetric Sasakian manifolds, Proc. Jangjeon Math. Soc., 11, 47 – 52 (2008). 11. U. C. De, M. M. Tripathi, Ricci tensor in 3-dimensional trans-Sasakian manifolds, Kyungpook Math. J., 43, 247 – 255 (2003). 12. S. Debnath, A. Bhattacharya, Second order parallel tensor in trans-Sasakian manifolds and connections with Ricci solitons, Lobachevskii J. Math., 33, 312 – 316 (2012). 13. L. P. Eisenhart, Symmetric tensor of the second order whose first covariant derivatives are zero, Trans. Amer. Math. Soc., 25, 297 – 306 (1923). 14. D. Friedan, Nonlinear models in 2 + \varepsilon -dimensions, Ann. Phys., 163, 318 – 419 (1985). 15. A. Ghosh, Kenmotsu 3-metric as Ricci solitons, Chaos, Solitons and Fractals, 44, 647 – 650 (2011). 16. A. Ghosh, Sasakian metric as a Ricci soliton and related results, J. Geom. and Phys., 75, 1 – 6 (2014). 17. A. Gray, L. M. Hervella, The sixteen classes of almost Hermitian manifolds and their linear invariants, Ann. Mat. Pura ed Appl., 123, 35 – 58 (1980). 18. R. S. Hamilton, The Ricci flow on surfaces, Mathematics and General Relativity, Contemp. Math., 71, 237 – 262 (1988). 19. B. Kagan, Über eine Erweiterung des Begriffes vom projektiven Raume und dem zugehörigen Absolut, Tensor Analysis, 1, 12 – 101 (1933). 20. H. Levy, Symmetric tensors of the second order whose covariant derivatives vanish, Ann. Math., 27, 91 – 98 (1925). 21. J. A. Oubina, New classes of almost contact metric structures, Publ. Math. Debrecen, 32, 187 – 193 (1985). 22. G. Perelman, The entropy formula for the Ricci flow and its geometric applications, arxiv math. DG. 1021111599. 23. D. G. Prakasha, B. S. Hadimani, \eta -Ricci solitons on para-Sasakian manifolds, J. Geom. (2016); DOI 10.1007/s00022- 016-0345-z. 24. R. Sharma, Certain results on K -contact and (K,\mu )-contact manifolds, J. Geom., 89, 138 – 147 (2008). 25. R. Sharma, Second order parallel tensors on contact manifolds, I, Algebra, Group, Geom., 7, 145 – 152 (1990). 26. T. Takahashi, Sasakian \phi -symmetric spaces, Tohoku Math. J., 29, 91 – 113 (1977). 27. M. Turan, U. C. De, A. Yildiz, Ricci solitons and gradient Ricci solitons in three-dimensional trans-Sasakian manifolds, Filomat, 26, 363 – 370 (2012). Received 08.06.17 ISSN 1027-3190. Укр. мат. журн., 2020, т. 72, № 3
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spelling umjimathkievua-article-60472020-05-26T09:20:33Z Some characterizations of three-dimensional trans-Sasakian manifolds admitting η- Ricci solitons and trans-Sasakian manifolds as Kagan subprojective space Деякi характеристики тривимiрних транс-многовидiв Сасакяна, що допускають η -солiтони Рiччi, та транс-многовиди Сасакяна як субпроективнi простори Кагана Деякi характеристики тривимiрних транс-многовидiв Сасакяна, що допускають η -солiтони Рiччi, та транс-многовиди Сасакяна як субпроективнi простори Кагана Sarkar, A. Sil, A. Paul, A. K. Саркар, А. Сіл, А. Пауль, А. К. UDC 514.7 The object of the present paper is to study three-dimensional trans-Sasakian manifolds admitting $\eta$-Ricci soliton. Actually, we study such manifolds whose Ricci tensor satisfy some special conditions like cyclic parallelity, Ricci semisymmetry, $\phi$-Ricci semisymmetry, after reviewing the properties of second order parallel tensors on such manifolds. We determine the form of Riemann curvature tensor of trans-Sasakian manifolds of dimension greater than three as Kagan subprojective spaces. We also give some classification results of trans-Sasakian manifolds of dimension greater than three as Kagan subprojective spaces. УДК 514.7 Вивчаються тривимірні транс-многовиди Сасакяна, які допускають $\eta$-солітони Річчі.  Власне, після огляду властивостей паралельних тензорів другого порядку на таких многовидах ми вивчаємо многовиди, тензор Річчі яких задовольняє деякі спеціальні умови, такі як циклічна паралельність, напівсиметрія Річчі, $\phi$-напівсиметрія Річчі.  Визначено форму тензора кривини Рімана для транс-многовидів Сасакяна, розмірність яких більша ніж 3, як субпроективних просторів Кагана.  Також наведено деякі класифікаційні результати для транс-многовидів Сасакяна, розмірність яких більша ніж 3, як субпроективних просторів Кагана.  Institute of Mathematics, NAS of Ukraine 2020-03-28 Article Article application/pdf https://umj.imath.kiev.ua/index.php/umj/article/view/6047 10.37863/umzh.v72i3.6047 Ukrains’kyi Matematychnyi Zhurnal; Vol. 72 No. 3 (2020); 427-432 Український математичний журнал; Том 72 № 3 (2020); 427-432 1027-3190 en https://umj.imath.kiev.ua/index.php/umj/article/view/6047/8685
spellingShingle Sarkar, A.
Sil, A.
Paul, A. K.
Саркар, А.
Сіл, А.
Пауль, А. К.
Some characterizations of three-dimensional trans-Sasakian manifolds admitting η- Ricci solitons and trans-Sasakian manifolds as Kagan subprojective space
title Some characterizations of three-dimensional trans-Sasakian manifolds admitting η- Ricci solitons and trans-Sasakian manifolds as Kagan subprojective space
title_alt Деякi характеристики тривимiрних транс-многовидiв Сасакяна, що допускають η -солiтони Рiччi, та транс-многовиди Сасакяна як субпроективнi простори Кагана
Деякi характеристики тривимiрних транс-многовидiв Сасакяна, що допускають η -солiтони Рiччi, та транс-многовиди Сасакяна як субпроективнi простори Кагана
title_full Some characterizations of three-dimensional trans-Sasakian manifolds admitting η- Ricci solitons and trans-Sasakian manifolds as Kagan subprojective space
title_fullStr Some characterizations of three-dimensional trans-Sasakian manifolds admitting η- Ricci solitons and trans-Sasakian manifolds as Kagan subprojective space
title_full_unstemmed Some characterizations of three-dimensional trans-Sasakian manifolds admitting η- Ricci solitons and trans-Sasakian manifolds as Kagan subprojective space
title_short Some characterizations of three-dimensional trans-Sasakian manifolds admitting η- Ricci solitons and trans-Sasakian manifolds as Kagan subprojective space
title_sort some characterizations of three-dimensional trans-sasakian manifolds admitting η- ricci solitons and trans-sasakian manifolds as kagan subprojective space
url https://umj.imath.kiev.ua/index.php/umj/article/view/6047
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