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  2. Convex function - Wikipedia

    en.wikipedia.org/wiki/Convex_function

    The function () = has ″ = >, so f is a convex function. It is also strongly convex (and hence strictly convex too), with strong convexity constant 2. The function () = has ″ =, so f is a convex function. It is strictly convex, even though the second derivative is not strictly positive at all points.

  3. Function of several complex variables - Wikipedia

    en.wikipedia.org/wiki/Function_of_several...

    ( i.e. be holomorphically convex.) such that f cannot be extended to any neighbourhood of x. i.e., let : be a holomorphic map, if every point has a neighborhood U such that () admits a -plurisubharmonic exhaustion function (weakly 1-complete [55]), in this situation, we call that X is locally pseudoconvex (or locally Stein) over Y. As an old ...

  4. Modulus and characteristic of convexity - Wikipedia

    en.wikipedia.org/wiki/Modulus_and_characteristic...

    The Banach space (X, ǁ ⋅ ǁ) is a strictly convex space (i.e., the boundary of the unit ball B contains no line segments) if and only if δ(2) = 1, i.e., if only antipodal points (of the form x and y = −x) of the unit sphere can have distance equal to 2. When X is uniformly convex, it admits an equivalent norm with power type modulus of ...

  5. Logarithmically concave function - Wikipedia

    en.wikipedia.org/wiki/Logarithmically_concave...

    This follows from the fact that the logarithm is monotone implying that the superlevel sets of this function are convex. [1] Every concave function that is nonnegative on its domain is log-concave. However, the reverse does not necessarily hold. An example is the Gaussian function f(x) = exp(−x 2 /2) which is log-concave since log f(x) = −x ...

  6. Mirror descent - Wikipedia

    en.wikipedia.org/wiki/Mirror_descent

    We are given convex function to optimize over a convex set , and given some norm ‖ ‖ on . We are also given differentiable convex function h : R n → R {\displaystyle h\colon \mathbb {R} ^{n}\to \mathbb {R} } , α {\displaystyle \alpha } - strongly convex with respect to the given norm.

  7. Strictly convex - Wikipedia

    en.wikipedia.org/wiki/Strictly_convex

    Strictly convex function, a function having the line between any two points above its graph; Strictly convex polygon, a polygon enclosing a strictly convex set of points; Strictly convex set, a set whose interior contains the line between any two points; Strictly convex space, a normed vector space for which the closed unit ball is a strictly ...

  8. Logarithmically convex function - Wikipedia

    en.wikipedia.org/.../Logarithmically_convex_function

    Strictly logarithmically convex if is strictly convex. Here we interpret ⁡ as . Explicitly, f is logarithmically convex if and only if, for all x 1, x 2X and all t ∈ [0, 1], the two following equivalent conditions hold:

  9. Bregman divergence - Wikipedia

    en.wikipedia.org/wiki/Bregman_divergence

    Let : be a continuously-differentiable, strictly convex function defined on a convex set. The Bregman distance associated with F for points p , q ∈ Ω {\displaystyle p,q\in \Omega } is the difference between the value of F at point p and the value of the first-order Taylor expansion of F around point q evaluated at point p :