
doi: 10.1007/bf01400254
This paper deals with properties of homotopies for finding roots of smooth mappings from \(R^ n\) to \(R^ n\). The homotopy considered is of the form: \(\Phi_ a(x,\lambda)=(1-\lambda)(x-a)+\lambda f(x)\), where x is a n-vector, f(x) is an n-vector and f is analytic in the real sense, and points \(x_ 0\) with \(f(x_ 0)=0\) are desired. Two new results are proven in the paper. The first states that, if \((1,x_ 0)\) is a limit point of the curve (x(t),\(\lambda\) (t)) which passes through (a,0), then there is a neighborhood of \((1,x_ 0)\) such that \((\Phi_ a)^{-1}(0)\) consists of finitely many parametrizable curves which can be represented by convergent fractional power series. This result is a significant statement about the behavior of homotopies when they converge to a root at which the Jacobian of f is singular. The second theorem states that the set of a for which the Jacobian of \(\Phi_ a\) is of full rank upon the interior of that component of \((\Phi_ a)^{-1}(0)\) which goes through (a,0) is open and dense. This is a stronger statement than statements based on Sard's theorem, which generally say that the set of a for which the Jacobian is rank-deficient has measure 0. The paper is carefully written.
singular solutions, convergent fractional power series, 510.mathematics, behavior of homotopies, Sard's theorem, Numerical computation of solutions to systems of equations, Article, homotopy methods
singular solutions, convergent fractional power series, 510.mathematics, behavior of homotopies, Sard's theorem, Numerical computation of solutions to systems of equations, Article, homotopy methods
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