6 found
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  1.  16
    Nondefinability results for expansions of the field of real numbers by the exponential function and by the restricted sine function.Ricardo Bianconi - 1997 - Journal of Symbolic Logic 62 (4):1173-1178.
    We prove that no restriction of the sine function to any (open and nonempty) interval is definable in $\langle\mathbf{R}, +, \cdot, , and that no restriction of the exponential function to an (open and nonempty) interval is definable in $\langle \mathbf{R}, +, \cdot, , where $\sin_0(x) = \sin(x)$ for x ∈ [ -π,π], and $\sin_0(x) = 0$ for all $x \not\in\lbrack -\pi,\pi\rbrack$.
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  2.  14
    Undefinability results in o-minimal expansions of the real numbers.Ricardo Bianconi - 2005 - Annals of Pure and Applied Logic 134 (1):43-51.
    We show that if is not in the field generated by α1,…,αn, then no restriction of the function xβ to an interval is definable in . We also prove that if the real and imaginary parts of a complex analytic function are definable in Rexp or in the expansion of by functions xα, for irrational α, then they are already definable in . We conclude with some conjectures and open questions.
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  3.  11
    Model completeness results for elliptic and abelian functions.Ricardo Bianconi - 1991 - Annals of Pure and Applied Logic 54 (2):121-136.
    We prove the model completeness of expansions of the reals by restricted elliptic and abelian functions. We make use of an auxiliary structure admitting quantifier elimination, where the basic relations are strongly definable in the original structure.
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  4.  70
    On sets ∀-definable from Pfaffian functions.Ricardo Bianconi - 1992 - Journal of Symbolic Logic 57 (2):688-697.
    We prove the existence of a bound to the number of components of an ∀-definable set in the reals, using Pfaffian functions, and give some applications.
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  5.  5
    On Sets $forall$-Definable From Pfaffian Functions.Ricardo Bianconi - 1992 - Journal of Symbolic Logic 57 (2):688-697.
    We prove the existence of a bound to the number of components of an $\forall$-definable set in the reals, using Pfaffian functions, and give some applications.
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  6.  13
    Some remarks on Schanuel's conjecture.Ricardo Bianconi - 2001 - Annals of Pure and Applied Logic 108 (1-3):15-18.
    Schanuel's Conjecture is the statement: if x 1 ,…,x n ∈ C are linearly independent over Q , then the transcendence degree of Q ,…, exp ) over Q is at least n . Here we prove that this is true if instead we take infinitesimal elements from any ultrapower of C , and in fact from any nonarchimedean model of the theory of the expansion of the field of real numbers by restricted analytic functions.
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