p. 271 - 276 Comparison theorems for half-linear differential equations of the fourth order J. Jaroš Received: January 9, 2011; Accepted: May 23, 2011 Abstract. An identity of the Picone type for fourth-order half-linear ordinary differential operators of the form where φ(u) := |u|α - 1u, α > 0, u Î R, and p, q, r, P, Q and R are continuous functions on a given interval I is derived and then Sturmian comparison theory for the corresponding fourth-order equations lα[x] = 0 and Lα[y] = 0 based on this identity is developed. Keywords: Picone's identity; half-linear differential equation; fourth order. AMS Subject classification: Primary: 34C10 PDF Compressed Postscript Version to read ISSN 0862-9544 (Printed edition) Faculty of Mathematics, Physics and Informatics Comenius University 842 48 Bratislava, Slovak Republic Telephone: + 421-2-60295111 Fax: + 421-2-65425882 e-Mail: amuc@fmph.uniba.sk Internet: www.iam.fmph.uniba.sk/amuc © 2011, ACTA MATHEMATICA UNIVERSITATIS COMENIANAE |