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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6

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    PublicationOpen Access
    A class of Banach algebras whose duals have the Schur property
    (TÜBİTAK, 1999) Mustafayev, H.; Department of Mathematics; Ülger, Ali; Faculty Member; Department of Mathematics; College of Sciences
    Call a commutative Banach algebra A a γ-algebra if it contains a bounded group Λ such that aco(Λ) contains a multiple of the unit ball of A. In this paper, first by exhibiting several concrete examples, we show that the class of γ-algebras is quite rich. Then, for a γ-algebra A, we prove that A* has the Schur property iff the Gelfand spectrum Σ of A is scattered iff A* = ap(A) iff A* = Span(Σ).
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    PublicationOpen Access
    Divisor function and bounds in domains with enough primes
    (Hacettepe Üniversitesi, 2019) Department of Mathematics; Göral, Haydar; Master Student; Department of Mathematics; College of Sciences
    In this note, first we show that there is no uniform divisor bound for the Bezout identity using Dirichlet's theorem on arithmetic progressions. Then, we discuss for which rings the absolute value bound for the Bezout identity is not trivial and the answer depends on the number of small primes in the ring.
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    PublicationOpen Access
    On elastic graph spines associated to quadratic Thurston maps
    (TÜBİTAK, 2022) Department of Mathematics; Yetişer, Ali Berkay; Faculty Member; Department of Mathematics; College of Sciences
    For a quadratic Thurston map having two distinct critical points and n postcritical points, we count the number of possible dynamical portraits. We associate elastic graph spines to several hyperbolic quadratic Thurston rational functions. These functions have four postcritical points, real coefficients, and invariant real intervals. The elastic graph spines are constructed such that each has embedding energy less than one. These are supporting examples to Dylan Thurston's recent positive characterization of rational maps. Using the same characterization, we prove that with a combinatorial restriction on the branched covering and a cycle condition on the dynamical portrait, a quadratic Thurston map with finite postcritical set of order n is combinatorially equivalent to a rational map. This is a special case of the Bernstein-Levy theorem.