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The birational point of view can afford to be careless about subsets of codimension 1. To have a moduli space as a scheme is on one side a question about characterising schemes as representable functors (as the Grothendieck school would see it); but geometrically it is more like a compactification question, as the stability criteria revealed.
Let : be a smooth map with hyperbolic fixed point at .We denote by () the stable set and by () the unstable set of .. The theorem [2] [3] [4] states that is a smooth manifold and its tangent space has the same dimension as the stable space of the linearization of at .
The fixed point a is stable if the absolute value of the derivative of f at a is strictly less than 1, and unstable if it is strictly greater than 1. This is because near the point a, the function f has a linear approximation with slope f'(a): () + ′ (). Thus
In his thesis, Boyce identified a pair of functions that commute under composition, but do not have a common fixed point, proving the fixed point conjecture to be false. [ 14 ] In 1963, Glenn Baxter and Joichi published a paper about the fixed points of the composite function h ( x ) = f ( g ( x ) ) = g ( f ( x ) ) {\displaystyle h(x)=f(g(x))=g ...
A fixed-point theorem is a result saying that at least one fixed point exists, under some general condition. [ 1 ] For example, the Banach fixed-point theorem (1922) gives a general criterion guaranteeing that, if it is satisfied, fixed-point iteration will always converge to a fixed point.
In mathematics, structural stability is a fundamental property of a dynamical system which means that the qualitative behavior of the trajectories is unaffected by small perturbations (to be exact C 1-small perturbations). Examples of such qualitative properties are numbers of fixed points and periodic orbits (but not their periods
The standard example is the action of C * on the plane C 2 defined as (,) = (,).The weight in the x-direction is 1 and the weight in the y-direction is -1.Thus by the Hilbert–Mumford criterion, a non-zero point on the x-axis admits 1 as its only weight, and a non-zero point on the y-axis admits -1 as its only weight, so they are both unstable; a general point in the plane admits both 1 and ...
In the mathematical field of model theory, a theory is called stable if it satisfies certain combinatorial restrictions on its complexity. Stable theories are rooted in the proof of Morley's categoricity theorem and were extensively studied as part of Saharon Shelah's classification theory, which showed a dichotomy that either the models of a theory admit a nice classification or the models ...