Yazar "De, Uday Chand" seçeneğine göre listele

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    Certain curvature conditions on generalized sasakian space-forms
    (Natl Inquiry Services Centre Pty Ltd, 2015) De, Uday Chand; Yildiz, Ahmet
    The object of the present paper is to study certain curvature conditions on generalized Sasakian space-forms. We classify generalized Sasakian space-forms which satisfy P P=0, P Z=0, Z P=0, Z Z=0, where P is the projective curvature tensor and Z is the concircular curvature tensor.
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    Certain results on a type of contact metric manifold
    (Springer Heidelberg, 2015) De, Uday Chand; Yildiz, Ahmet; Cetinkaya, Azime
    Let M be a 3-dimensional almost contact metric manifold satisfying (*) condition. We denote such a manifold by M*. At first we study symmetric and skew-synunetric parallel tensor of type (0, 2) in M*. Next we prove that a non-cosymplectic manifold M* is Ricci semisymmetric if and only if it is Einstein. Also we study locally phi-symmetry and eta-parallel Ricci tensor of M*. Finally, we prove that if a non-cosymplectic M* is Einstein, then the manifold is Sasakian.
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    Characterizations of mixed quasi-Einstein manifolds
    (World Scientific Publ Co Pte Ltd, 2017) Mallick, Sahanous; Yildiz, Ahmet; De, Uday Chand
    The object of the present paper is to study mixed quasi-Einstein manifolds. Some geometric properties of mixed quasi-Einstein manifolds have been studied. We also discuss M(QE)(4) spacetime with space-matter tensor and some properties related to it. Finally, we construct an example of a mixed quasi-Einstein spacetime.
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    Generalized Quasi-Einstein Metrics and Contact Geometry
    (Kyungpook Natl Univ, Dept Mathematics, 2022) Biswas, Gour Gopal; De, Uday Chand; Yildiz, Ahmet
    The aim of this paper is to characterize K-contact and Sasakian manifolds whose metrics are generalized quasi-Einstein metric. It is proven that if the metric of a K-contact manifold is generalized quasi-Einstein metric, then the manifold is of constant scalar curvature and in the case of a Sasakian manifold the metric becomes Einstein under certain restriction on the potential function. Several corollaries have been provided. Finally, we consider Sasakian 3-manifold whose metric is generalized quasi-Einstein metric.
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    A note on almost quasi Yamabe solitons and gradient almost quasi Yamabe solitons
    (Hacettepe Univ, Fac Sci, 2021) Ghosh, Sujit; De, Uday Chand; Yildiz, Ahmet
    In this article, we characterize almost quasi-Yamabe solitons and gradient almost quasiYamabe solitons in context of three dimensional Kenmotsu manifolds. It is proven that if the metric of a three dimensional Kenmotsu manifold admits an almost quasi-Yamabe soliton with soliton vector field W then the manifold is of constant sectional curvature -1, but the converse is not true has been shown by a concrete example, under the restriction phi W not equal 0. Next we consider gradient almost quasi-Yamabe solitons in a three dimensional Kenmotsu manifold.
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    ON A CLASS OF N(k)-CONTACT METRIC MANIFOLDS
    (Editura Acad Romane, 2014) De, Uday Chand; Yildiz, Ahmet; Ghosh, Sujit
    The object of the present paper is to study xi-concircularly flat and phi-concircularly flat N(k)-contact metric manifolds. Beside these, we also study N(k)-contact metric manifolds satisfying Z(xi, X).S = 0. Finally, we construct an example to verify some results.
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    ON A TYPE OF LORENTZIAN PARA-SASAKIAN MANIFOLDS
    (Editura Acad Romane, 2014) Yildiz, Ahmet; De, Uday Chand; Ata, Erhan
    The object of the present paper is to introduce a new concept called generalized eta-Einstein manifold in a Lorentzian Para-Sasakian manifold. Some geometric properties have been studied. Finally an example has been constructed to prove the existance of a generalized eta-Einstein Lorentzian Para-Sasakian manifold.
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    On some classes of 3-dimensional generalized (?, ?)-contact metric manifolds
    (Tubitak Scientific & Technological Research Council Turkey, 2015) Yildiz, Ahmet; De, Uday Chand; Cetinkaya, Azime
    The object of the present paper is to obtain a necessary and sufficient condition for a 3-dimensional generalized (kappa, mu)-contact metric manifold to be locally phi-symmetric in the sense of Takahashi and the condition is verified by an example. Next we characterize a 3-dimensional generalized (kappa, mu)-contact metric manifold satisfying certain curvature conditions on the concircular curvature tensor. Finally, we construct an example of a generalized (kappa, mu)-contact metric manifold to verify Theorem 1 of our paper.
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    On some classes of 3-dimensional generalized (?, µ)-contact metric manifolds
    (2015) Yıldız, Ahmet; De, Uday Chand; Çetinkaya, Azime
    Abstract: The object of the present paper is to obtain a necessary and sufficient condition for a 3 -dimensional generalized (κ, µ) -contact metric manifold to be locally ϕ-symmetric in the sense of Takahashi and the condition is verified by an example. Next we characterize a 3 -dimensional generalized (κ, µ) -contact metric manifold satisfying certain curvature conditions on the concircular curvature tensor. Finally, we construct an example of a generalized (κ, µ) -contact metric manifold to verify Theorem 1 of our paper.
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    Some results on paracontact metric (k, ?)-manifolds with respect to the Schouten-van Kampen connection
    (Hacettepe Univ, Fac Sci, 2022) Perktas, Selcen Yuksel; De, Uday Chand; Yildiz, Ahmet
    In the present paper we study certain symmetry conditions and some types of solitons on paracontact metric (k, mu)-manifolds with respect to the Schouten-van Kampen connection. We prove that a Ricci semisymmetric paracontact metric (k, mu)-manifold with respect to the Schouten-van Kampen connection is an g-Einstein manifold. We investigate paracontact metric (k, mu)-manifolds satisfying (sic) . (sic)(cur) = 0 with respect to the Schouten-van Kampen connection. Also, we show that there does not exist an almost Ricci soliton in a (2n + 1)-dimensional paracontact metric (k, mu)-manifold with respect to the Schouten-van Kampen connection such that k > -1 or k < -1. In case of the metric is being an almost gradient Ricci soliton with respect to the Schouten-van Kampen connection, then we state that the manifold is either N(k)-paracontact metric manifold or an Einstein manifold. Finally, we present some results related to almost Yamabe solitons in a paracontact metric (k, mu)-manifold equipped with the Schouten-van Kampen connection and construct an example which verifies some of our results.