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Coste, M. and Ruiz Sancho, Jesús María and Shiota, Masahiro
(1996)
*Separation, factorization and finite sheaves on Nash manifolds.*
Compositio Mathematica, 103
(1).
pp. 31-62.
ISSN 0010-437X

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Official URL: http://archive.numdam.org/ARCHIVE/CM/CM_1996__103_1/CM_1996__103_1_31_0/CM_1996__103_1_31_0.pdf

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## Abstract

Nash functions are those real analytic functions which are algebraic over the polynomials. Let M⊂Rn be a Nash manifold, N(M) the ring of Nash functions on M and O(M) the ring of analytic functions on M. The following problems have been open for at least twenty years: (1) Separation problem: Let G be a prime ideal of N(M); is G⋅O(M) a prime ideal? (2) Factorisation problem: Given f∈N(M) and an analytic factorisation f=f1⋅f2, do there exist Nash functions g1,g2 on M and positive analytic functions φ1,φ2 such that φ1⋅φ2=1 and f1=φ1g1, f2=φ2g2? (3) Global equations problem: Is every finite sheaf I of ideals of N generated by global Nash functions? (4) Extension problem: For the same I as above, is the natural homomorphism H0(M,N)→H0(M,N/I) surjective? The main results of this paper are: Theorem. For any Nash manifold M, Problem 1 has a positive answer if and only if Problem 3 (or Problem 4) have a positive answer. Problem 3 has a positive answer for any locally principal finite sheaf if and only if Problem 2 has a positive answer. It is interesting to remark that the authors, in a recent paper, have proved that the above problems have a positive answer under the hypothesis that M be compact.

Item Type: | Article |
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Uncontrolled Keywords: | Extension theorem; Nash functions; Nash manifolds |

Subjects: | Sciences > Mathematics > Algebraic geometry Sciences > Mathematics > Set theory Sciences > Mathematics > Topology |

ID Code: | 20011 |

Deposited On: | 20 Feb 2013 17:51 |

Last Modified: | 12 Dec 2018 15:13 |

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