Displaying similar documents to “Intersections of analytic sets with linear subspaces”

Relations among analytic functions. II

Edward Bierstone, P. D. Milman (1987)

Annales de l'institut Fourier

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This is a sequel to “Relations among analytic functions I”, , , fasc. 1, [pp. 187-239]. We reduce to semicontinuity of local invariants the problem of finding 𝒞 ∞ solutions to systems of equations involving division and composition by analytic functions. We prove semicontinuity in several general cases : in the algebraic category, for “regular” mappings, and for module homomorphisms over a finite mapping.

Approximation of C ∞ -functions without changing their zero-set

F. Broglia, A. Tognoli (1989)

Annales de l'institut Fourier

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For a C ∞ function ϕ : M → ℝ (where M is a real algebraic manifold) the following problem is studied. If ϕ - 1 ( 0 ) is an algebraic subvariety of M , can ϕ be approximated by rational regular functions f such that f - 1 ( 0 ) = ϕ - 1 ( 0 ) ? We find that this is possible if and only if there exists a rational regular function g : M → ℝ such that g - 1 ( 0 ) = ϕ - 1 ( 0 ) and g(x) · ϕ ( x ) ≥ 0 for any x in ℝ n . Similar results are obtained also in the analytic and in the Nash cases. For non approximable functions the minimal flatness locus...