
Definition of convexity - Mathematics Stack Exchange
Jan 14, 2017 · A different definition is that a function is convex iff its epigraph is convex. This is a visually intuitive definition, and it explains why we use the same word "convex" for both sets …
real analysis - Difference between convexity and strict convexity ...
May 14, 2018 · So, is there a way to distinguish convexity and strict convexity just by visual inspection of the graph of a function? And, if so, how? What can be the specific characteristic …
Convexity definition confusion - Mathematics Stack Exchange
Apr 3, 2014 · Joint convexity means that the restriction of the function to any segment is a convex function of a single variable. Element-wise convexity means that only vertical and horizontal …
Definition of strongly convex - Mathematics Stack Exchange
1 It is easy to prove if you write out (2) based on the definition of convex function. Then what you need to know is that f (.) is convex and the norm is convex. Here any norm is ok, because of …
real analysis - Midpoint-convexity and continuity implies convexity ...
It's more correct to say that he proved Jensen's Inequality (with arbitrary real weights) for functions which are midpoint convex and continuous. Of course, Jensen's Inequality with two …
First order condition for a convex function
Aug 29, 2020 · For the definition of convexity, the graphical perspective is that the line joining any two points is always above the region of the function values in between these points. what …
Proof for strongly convex function is strictly convex
Jan 10, 2017 · Why you taking derivatives ? Write down the definition of strong-convexity without using assuming / gradients. Let the modulus of convexity tend to zero; you obtain the definition …
Topological definition of Convexity - Mathematics Stack Exchange
Jun 3, 2020 · There is a general topology flavoured definition of a general convexity space, which generalises the already existing notions of convexity that have been defined in the past.
How to check if a function is convex - Mathematics Stack Exchange
Aug 16, 2019 · 21 What you gave is the standard definition of a convex function. If f is supposed to be continuous, it is enough to check that f (x + y 2) ≤ f(x) + f(y) 2 for all x, y. If f is twice …
Question on equivalent definitions of a convex function
It is well known that one equivalent definition of convexity is the statement that the gradient of secant lines increase. One way to write this down is as follows: for all $x<y<z$,