Now showing items 1-20 of 613

    • Extremely charged static dust distributions in general relativity 

      Gürses, Metin (World Scientific, 1998)
      Conformo static charged dust distributions are investigated in the framework of general relativity. Einstein’s equations reduce to a non-linear version of Poisson’s equation and Maxwell’s equations imply the equality of ...
    • Complete intersection monomial curves and the Cohen—Macaulayness of their tangent cones 

      Katsabekis, Anargyros (World Scientific Publishing, 2019)
      Let C(n) be a complete intersection monomial curve in the 4-dimensional affine space. In this paper we study the complete intersection property of the monomial curve C(n + wv), where w > 0 is an integer and v ∈ ℕ4. In ...
    • Black hole solutions and Euler equation in Rastall and generalized Rastall theories of gravity 

      Moradpour, H.; Heydarzade, Yaghoub; Corda, C.; Ziaie, A. H.; Ghaffari, S. (World Scientific Publishing, 2019)
      Focusing on the special case of generalized Rastall theory, as a subclass of the non-minimal curvature-matter coupling theories in which the field equations are mathematically similar to the Einstein field equations in the ...
    • Sequential warped products: curvature and conformal vector fields 

      Chand De, Uday; Shenawy, S.; Ünal, Bülent (University of Nis, 2019)
      In this note, we introduce a new type of warped products called as sequential warped products to cover a wider variety of exact solutions to Einstein’s field equation. First, we study the geometry of sequential warped ...
    • Longest increasing subsequences in involutions avoiding patterns of length three 

      Mansour, T.; Yıldırım, Gökhan (TÜBİTAK, 2019-07)
      We study the longest increasing subsequences in random involutions that avoid the patterns of length three under the uniform probability distribution. We determine the exact and asymptotic formulas for the average length ...
    • On the Cohen–Macaulayness of tangent cones of monomial curves in A 4 (K) 

      Arslan, F.; Katsabekis, Anargyros; Nalbandıyan, M. (TÜBİTAK, 2019-05)
      In this paper we give necessary and sufficient conditions for the Cohen–Macaulayness of the tangent cone of a monomial curve in 4-dimensional affine space. We particularly study the case where C is a Gorenstein noncomplete ...
    • An observation on the module structure of block algebras 

      Gelvin, Matthew J. K. (Taylor & Francis, 2019-05-26)
      Let B be a p-block of the finite group G. We observe that the p-fusion of G constrains the module structure of B: Any basis of B that is closed under the left and right multiplications of a chosen Sylow p-subgroup S of G ...
    • A model structure via orbit spaces for equivariant homotopy 

      Erdal, Mehmet Akif; Güçlükan İlhan, Aslı (Springer, 2019-06-26)
      Let G be discrete group and FF be a collection of subgroups of G. We show that there exists a left induced model structure on the category of right G-simplicial sets, in which the weak equivalences and cofibrations are the ...
    • Cohomology of infinite groups realizing fusion systems 

      Gündoğan, Muhammed Said; Yalçın, Ergün (Springer, 2019-06-07)
      Given a fusion system FF defined on a p-group S, there exist infinite group models, constructed by Leary and Stancu, and Robinson, that realize FF. We study these models when FF is a fusion system of a finite group G and ...
    • Cosmological singularities in conformal Weyl gravity 

      Heydarzade, Yaghoub (Springer, 2019-11)
      In this work, we study the issue of the past and future cosmological singularities in the context of the fourth-order conformal Weyl gravity. In particular, we investigate the emergent universe scenario proposed by Ellis ...
    • Almost unit-clean rings 

      Chen, H.; Köse, H.; Kurtulmaz, Yosum (Editura Academiei Romane, 2019)
      A ring R is almost unit-clean provided that every element in R is equivalent to the sum of an idempotent and a regular element. We investigate conditions under which a ring is almost unit-clean. We prove that every ring ...
    • Smooth models of singular K3-surfaces 

      Degtyarev, Alexander (European Mathematical Society Publishing House, 2019)
    • Bifurcation analysis of the dynamics of interacting subnetworks of a spiking network 

      Lagzi, F.; Atay, Fatihcan M.; Rotter, S. (Nature Publishing Group, 2019-08)
      We analyze the collective dynamics of hierarchically structured networks of densely connected spiking neurons. These networks of sub-networks may represent interactions between cell assemblies or diferent nuclei in the ...
    • Non-Einsteinian black holes in generic 3D gravity theories 

      Gürses, Metin; Şişman, T. Ç.; Tekin, B. (American Physical Society, 2019)
      The Bañados-Teitelboim-Zanelli (BTZ) black hole metric solves the three-dimensional Einstein’s theory with a negative cosmological constant as well as all the generic higher derivative gravity theories based on the metric; ...
    • New classes of spherically symmetric, inhomogeneous cosmological models 

      Gürses, Metin; Heydarzade, Yaghoub (American Physical Society, 2019)
      We present two classes of inhomogeneous, spherically symmetric solutions of the Einstein-Maxwell-perfect fluid field equations with cosmological constant generalizing the Vaidya-Shah solution. Some special limits of our ...
    • A short note on Isaacs–Navarro’s theorem 

      Kızmaz, M. Yasir (Birkhauser Verlag AG, 2019)
      In this short note, we give a character free proof to a result of Isaacs–Navarro.
    • A Modified Gravity Theory: Null Aether* 

      Gürses, Metin; Şentürk, Çetin (Chinese Physical Society and IOP Publishing, 2019-03-01)
      General quantum gravity arguments predict that Lorentz symmetry might not hold exactly in nature. This has motivated much interest in Lorentz breaking gravity theories recently. Among such models are vector-tensor theories ...
    • Invariant weakly positive semidefinite kernels with values in topologically ordered ∗-spaces 

      Ay, Serdar; Gheondea, Aurelian (Instytut Matematyczny PAN, 2019)
      We consider weakly positive semidefinite kernels valued in ordered ∗-spaces with or without certain topological properties, and investigate their linearisations (Kolmogorov decompositions) as well as their reproducing ...
    • Local comparability of exchange ideals 

      Köse, H.; Kurtulmaz, Yosum; Chen, H. (Hacettepe University, 2019)
      An exchange ideal I of a ring R is locally comparable if for every regular x ∈ I there exists a right or left invertible u ∈ 1+I such that x = xux. We prove that every matrix extension of an exchange locally comparable ...
    • An inversion formula for the primitive idempotents of the trivial source algebra 

      Barker, Laurence (Elsevier, 2019)
      Formulas for the primitive idempotents of the trivial source algebra, in characteristic zero, have been given by Boltje and Bouc–Thévenaz. We shall give another formula for those idempotents, expressing them as linear ...