192 research outputs found

    Engagement Letters

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    Degree spectra for transcendence in fields

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    We show that for both the unary relation of transcendence and the finitary relation of algebraic independence on a field, the degree spectra of these relations may consist of any single computably enumerable Turing degree, or of those c.e. degrees above an arbitrary fixed Δ20\Delta^0_2 degree. In other cases, these spectra may be characterized by the ability to enumerate an arbitrary Σ20\Sigma^0_2 set. This is the first proof that a computable field can fail to have a computable copy with a computable transcendence basis

    Nonlinear Differential Equations Satisfied by Certain Classical Modular Forms

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    A unified treatment is given of low-weight modular forms on \Gamma_0(N), N=2,3,4, that have Eisenstein series representations. For each N, certain weight-1 forms are shown to satisfy a coupled system of nonlinear differential equations, which yields a single nonlinear third-order equation, called a generalized Chazy equation. As byproducts, a table of divisor function and theta identities is generated by means of q-expansions, and a transformation law under \Gamma_0(4) for the second complete elliptic integral is derived. More generally, it is shown how Picard-Fuchs equations of triangle subgroups of PSL(2,R) which are hypergeometric equations, yield systems of nonlinear equations for weight-1 forms, and generalized Chazy equations. Each triangle group commensurable with \Gamma(1) is treated.Comment: 40 pages, final version, accepted by Manuscripta Mathematic

    Congruences for Fourier coefficients of half-integral weight modular forms and special values of L-functions

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    Congruences for Fourier coefficients of integer weight modular forms have been the focal point of a number of investigations. In this note we shall ex-hibit congruences for Fourier coefficients of a slightly different type. Let f(z) =P∞ n=0 a(n)q n be a holomorphic half integer weight modular form with integer coef-ficients. If ` is prime, then we shall be interested in congruences of the form a(`N) ≡ 0 mod ` where N is any quadratic residue (resp. non-residue) modulo `. For every prime `> 3 we exhibit a natural holomorphic weight ` 2 +1 modular form whose coefficients satisfy the congruence a(`N) ≡ 0 mod ` for every N satisfying `−

    Obituary

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    n Vergelykende ondersoek na die effektiwiteit van verskillende konvensionele en minimum grondbewerkingspraktyke in die wingerdbou ten opsigte van grondvogbewaring en ander fisiese eienskappe

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    Proefskrif (M. Sc. Agric.) -- Universiteit van Stellenbosch, 1977.Full text to be digitised and attached to bibliographic record
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