Ky Fan's inequality seems rather beautiful. The most beautiful proof can be found here

Jovanović, Milan V.; Pogány, Tibor K.; Sándor, József, Notes on certain inequalities by Hölder, Lewent and Ky Fan, J. Math. Inequal. 1, No. 1, 53-55 (2007). ZBL1147.26011, MR2347705.

Ky Fan's inequality seems rather beautiful. The most beautiful proof can be found here

Jovanović, Milan V.; Pogány, Tibor K.; Sándor, József, Notes on certain inequalities by Hölder, Lewent and Ky Fan, J. Math. Inequal. 1, No. 1, 53-55 (2007). ZBL1147.26011, MR2347705.

Ky Fan's inequality seems rather beautiful. The most beatiful proof can be found here http://files.ele-math.com/articles/jmi-01-07.pdf

Ky Fan's inequality seems rather beautiful. The most beautiful proof can be found here

Jovanović, Milan V.; Pogány, Tibor K.; Sándor, József, Notes on certain inequalities by Hölder, Lewent and Ky Fan, J. Math. Inequal. 1, No. 1, 53-55 (2007). ZBL1147.26011, MR2347705.