Two Alternative Proofs of the Grüss Inequality
The classical Grüs inequality has spurred a range of improvements, generalizations, and extensions. In this article, we provide new functional bounds that ultimately lead to two elementary proofs of the inequality that might be of interest. Our results are motivated by the extreme cases where the equality is reached, namely step functions of equal support. Our first proof is based on the standard Cauchy-Schwarz inequality and a simple bound on the variance of a function. Its simplicity would be of particular interest to those who are new to the study of functional inequalities. Our second proof utilizes non-intuitive and novel bounds on functionals defined on L∞(0, 1). As a result, we provide a detailed and new insight into the nature of the Grüss inequality.
Keywords:Inequalities, Gruss inequality, Functional inequalities
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