{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,26]],"date-time":"2026-08-26T16:14:47Z","timestamp":1787760887005,"version":"build-2784847793"},"reference-count":22,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2018,3,9]],"date-time":"2018-03-09T00:00:00Z","timestamp":1520553600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Let Z be a standard Gaussian random variable, X be independent of Z, and t be a strictly positive scalar. For the derivatives in t of the differential entropy of     X +  t  Z    , McKean noticed that Gaussian X achieves the extreme for the first and second derivatives, among distributions with a fixed variance, and he conjectured that this holds for general orders of derivatives. This conjecture implies that the signs of the derivatives alternate. Recently, Cheng and Geng proved that this alternation holds for the first four orders. In this work, we employ the technique of linear matrix inequalities to show that: firstly, Cheng and Geng\u2019s method may not generalize to higher orders; secondly, when the probability density function of     X +  t  Z     is log-concave, McKean\u2019s conjecture holds for orders up to at least five. As a corollary, we also recover Toscani\u2019s result on the sign of the third derivative of the entropy power of     X +  t  Z    , using a much simpler argument.<\/jats:p>","DOI":"10.3390\/e20030182","type":"journal-article","created":{"date-parts":[[2018,3,9]],"date-time":"2018-03-09T12:17:41Z","timestamp":1520597861000},"page":"182","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["Gaussian Optimality for Derivatives of Differential Entropy Using Linear Matrix Inequalities"],"prefix":"10.3390","volume":"20","author":[{"given":"Xiaobing","family":"Zhang","sequence":"first","affiliation":[{"name":"Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050, China"},{"name":"School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China"},{"name":"University of Chinese Academy of Sciences, Beijing 100049, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Venkat","family":"Anantharam","sequence":"additional","affiliation":[{"name":"Department of Electrical Engineering and Computer Sciences (EECS), University of California, Berkeley, CA 94720-1234, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yanlin","family":"Geng","sequence":"additional","affiliation":[{"name":"School of Information Science and Technology, ShanghaiTech University, Shanghai 201210, China"},{"name":"Shanghai Institute of Fog Computing Technology, Shanghai Tech University, Shanghai 201210, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2018,3,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"379","DOI":"10.1002\/j.1538-7305.1948.tb01338.x","article-title":"A mathematical theory of communication","volume":"27","author":"Shannon","year":"1948","journal-title":"Bell Syst. 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