Search results
Results From The WOW.Com Content Network
The function f(x) = √ x defined on [0, 1] is not Lipschitz continuous. This function becomes infinitely steep as x approaches 0 since its derivative becomes infinite. However, it is uniformly continuous, [8] and both Hölder continuous of class C 0, α for α ≤ 1/2 and also absolutely continuous on [0, 1] (both of which imply the former).
In general, the modulus of continuity of a uniformly continuous function on a metric space needs to take the value +∞. For instance, the function f : N → R such that f(n) := n 2 is uniformly continuous with respect to the discrete metric on N, and its minimal modulus of continuity is ω f (t) = +∞ for any t≥1, and ω f (t) = 0 otherwise ...
A function f with variable x is continuous at the real number c, if the limit of (), as x tends to c, is equal to (). There are several different definitions of the (global) continuity of a function, which depend on the nature of its domain .
Part I of the theorem then says: if f is any Lebesgue integrable function on [a, b] and x 0 is a number in [a, b] such that f is continuous at x 0, then = is differentiable for x = x 0 with F′(x 0) = f(x 0). We can relax the conditions on f still further and suppose that it is merely locally integrable.
Theorem [7] [8] — A linear map between two F-spaces (e.g. Banach spaces) is continuous if and only if its graph is closed. The theorem is a consequence of the open mapping theorem ; see § Relation to the open mapping theorem below (conversely, the open mapping theorem in turn can be deduced from the closed graph theorem).
Pavel Urysohn. In topology, the Tietze extension theorem (also known as the Tietze–Urysohn–Brouwer extension theorem or Urysohn-Brouwer lemma [1]) states that any real-valued, continuous function on a closed subset of a normal topological space can be extended to the entire space, preserving boundedness if necessary.
The usual proof of the closed graph theorem employs the open mapping theorem.It simply uses a general recipe of obtaining the closed graph theorem from the open mapping theorem; see closed graph theorem § Relation to the open mapping theorem (this deduction is formal and does not use linearity; the linearity is needed to appeal to the open mapping theorem which relies on the linearity.)
More generally, the measure μ is assumed to be locally finite (rather than finite) and F(x) is defined as μ((0,x]) for x > 0, 0 for x = 0, and −μ((x,0]) for x < 0. In this case μ is the Lebesgue–Stieltjes measure generated by F. [17] The relation between the two notions of absolute continuity still holds. [18]