2016
DOI: 10.1307/mmj/1457101814
|View full text |Cite
|
Sign up to set email alerts
|

On trace-convex noncommutative polynomials

Abstract: Abstract. To each continuous function f : R → R there is an associated trace function on n × n real symmetric matrices Tr f . The classical Klein lemma states that f is convex if and only if Tr f is convex. In this note we present an algebraic strengthening of this lemma for univariate polynomials f : Tr f is convex if and only if the noncommutative second directional derivative of f is a sum of hermitian squares and commutators in the free algebra. We also give a localized version of this result.

Help me understand this report
View preprint versions

Search citation statements

Order By: Relevance

Paper Sections

Select...
1

Citation Types

0
2
0

Year Published

2020
2020
2021
2021

Publication Types

Select...
1
1

Relationship

0
2

Authors

Journals

citations
Cited by 2 publications
(2 citation statements)
references
References 27 publications
(26 reference statements)
0
2
0
Order By: Relevance
“…Similarly, we say a function is trace convex if tr f A+B 2 ≤ tr f (A)+f (B) 2 . As happened in the case of monotonicity, a function f is trace convex if and only if f is convex [8,13]. In multivariable settings, the theory of joint trace convexity depends intensely on the expression being analyzed [9,2,3].…”
Section: Introductionmentioning
confidence: 99%
See 1 more Smart Citation
“…Similarly, we say a function is trace convex if tr f A+B 2 ≤ tr f (A)+f (B) 2 . As happened in the case of monotonicity, a function f is trace convex if and only if f is convex [8,13]. In multivariable settings, the theory of joint trace convexity depends intensely on the expression being analyzed [9,2,3].…”
Section: Introductionmentioning
confidence: 99%
“…In general, the current theory of tracial inequalities is real analytic and the theory of matrix inequalities is complex analytic. We give a class of trace functions that have nice complex analytic properties, which contrasts to existing literature [9,8,2,3,13].…”
mentioning
confidence: 96%