Journal of Inequalities in Pure and Applied Mathematics HILBERT-PACHPATTE TYPE INTEGRAL INEQUALITIES AND THEIR IMPROVEMENT volume 4, issue 1, article 16, 2003. S.S. DRAGOMIR AND YOUNG-HO KIM School of Computer Science and Mathematics Victoria University of Technology PO Box 14428 , Melbourne City MC Victoria 8001, Australia. EMail: sever.dragomir@vu.edu.au URL: http://rgmia.vu.edu.au/SSDragomirWeb.html Department of Applied Mathematics Changwon National University Changwon 641-773, Korea. EMail: yhkim@sarim.changwon.ac.kr Received 31 October, 2002; accepted 8 January, 2003. Communicated by: P.S. Bullen Abstract Contents JJ J II I Home Page Go Back Close c 2000 Victoria University ISSN (electronic): 1443-5756 114-02 Quit Abstract In this paper, we obtain an extension of multivariable integral inequality of Hilbert-Pachpatte type. By specializing the upper estimate functions in the hypothesis and the parameters, we obtain many special cases. 2000 Mathematics Subject Classification: 26D15. Key words: Hilbert’s inequality, Hilbert-Pachpatte type inequality, Hölder’s inequality, Jensen inequality. The authors would like to thank Professor P.S. Bullen, University of British Columbia, Canada, for the careful reading of the manuscript which led to a considerable improvement in the presentation of this paper. Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents 1 Intoduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2 Main Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 3 The Various Inequalities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 References Contents JJ J II I Go Back Close Quit Page 2 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au 1. Intoduction Hilbert’s double series theorem [3, p. 226] was proved first by Hilbert in his lectures on integral equations. The determination of the constant, the integral analogue, the extension, other proofs of the whole or of parts of the theorems and generalizations in different directions have been given by several authors (cf. [3, Chap. 9]). Specifically, in [10] – [14] the author has established some new inequalities similar to Hilbert’s double-series inequality and its integral analogue which we believe will serve as a model for further investigation. Recently, G.D. Handley, J.J. Koliha and J.E. Pečarić [2] established a new class of related integral inequalities from which the results of Pachpatte [12] – [14] are obtained by specializing the parameters and the functions Φi . A representative sample is the following. Theorem 1.1 (Handley, Koliha and Pečarić [2, Theorem 3.1]). Let ui ∈ C mi ([0, xi ]) for i ∈ I. If Z si (ki ) (si − τi )mi −ki −1 Φi (τi ) dτi , si ∈ [0, xi ], i ∈ I, ui (si ) ≤ 0 then Z S.S. Dragomir and Young-Ho Kim Title Page Contents JJ J II I Go Back x1 Z ··· 0 Hilbert-Pachpatte Type Integral Inequalities and their Improvement 0 xn Qn (ki ) u (s ) i i=1 i ds1 · · · dsn Pn (αi +1)/(qi ωi ) i=1 ωi si p1 n n Z xi 1 Y Y i qi βi +1 pi ≤U xi (xi − si ) Φi (si ) dsi , i=1 i=1 0 Close Quit Page 3 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au where U = 1 .Q n i=1 [(αi 1 1 + 1) qi (βi + 1) pi ] . The purpose of the present paper is to derive an extension of the inequality given in Theorem 1.1. In addition, we obtain some new inequalities as HilbertPachpatte type inequalities, these inequalities improve the results obtained by Handley, Koliha and Pečarić [2]. Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents JJ J II I Go Back Close Quit Page 4 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au 2. Main Results In what follows we denote by R the set of real numbers; R+ denotes the interval [0, ∞). The symbols N, Z have their usual meaning. The following notation and hypotheses will be used throughout the paper: I = {1, ..., n} n∈N mi , i ∈ I mi ∈ N ki , i ∈ I ki ∈ {0, 1, . . . , mi − 1} Hilbert-Pachpatte Type Integral Inequalities and their Improvement xi , i ∈ I xi ∈ R, xi > 0 S.S. Dragomir and Young-Ho Kim pi , q i , i ∈ I pi , qi ∈ R, pi , qi > 0, p1i + q1i = 1 Pn 1 1 Pn 1 1 = i=1 pi , q = i=1 qi p p, q ai , bi , i ∈ I ωi , i ∈ I a i , bi ∈ R + , a i + b i = 1 P ωi ∈ R, ωi > 0, ni=1 ωi = Ωn αi , i ∈ I αi = (ai + bi qi )(mi − ki − 1) βi , i ∈ I βi = ai (mi − ki − 1) Title Page Contents JJ J II I Go Back m0i ([0, xi ]) for some m0i ≥ mi ui , i ∈ I ui ∈ C Φi , i ∈ I Φi ∈ C 1 ([0, xi ]), Φi ≥ mi . Close Quit Page 5 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au Here the ui are given functions of sufficient smoothness, and the Φi are subject to choice. The coefficients pi , qi are conjugate Hölder exponents to be used in applications of Hölder’s inequality, and the coefficients ai , bi will be used in exponents to factorize integrands. The coefficients ωi will act as weights in applications of the geometric-arithmetic mean inequality. The coefficients αi and βi arise naturally in the derivation of the inequalities. Our main results are given in the following theorems. Theorem 2.1. Let ui ∈ C mi ([0, xi ]) for i ∈ I. If Z si (ki ) (2.1) (si − τi )mi −ki −1 Φi (τi ) dτi , ui (si ) ≤ si ∈ [0, xi ], i ∈ I, Hilbert-Pachpatte Type Integral Inequalities and their Improvement 0 S.S. Dragomir and Young-Ho Kim then Z x1 Z ··· (2.2) 0 0 xn h 1 Ωn Qn (ki ) u (s ) i i i=1 iΩn ds1 · · · dsn Pn (αi +1)/(qi ωi ) i=1 ωi si p1 n n Z xi 1 Y Y i qi βi +1 pi ≤V xi (xi − si ) Φi (si ) dsi , i=1 0 i=1 Contents JJ J II I Go Back where (2.3) Title Page V =Q h n i=1 Close 1 1 qi (αi + 1) (βi + 1) 1 pi i. Proof. Factorize the integrand on the right side of (2.1) as (si − τi )(ai /qi +bi )(mi −ki −1) × (si − τi )(ai /pi )(mi −ki −1) Φi (τi ) Quit Page 6 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au and apply Hölder’s inequality [9, p.106]. Then q1 Z s i i (ki ) (ai +bi qi )(mi −ki −1) (si − τi ) dτi ui (si ) ≤ 0 Z si × ai (mi −ki −1) (si − τi ) p1 pi Φi (τi ) dτi i 0 = (α +1)/qi si i (αi + 1) si Z 1 qi βi pi (si − τi ) Φi (τi ) dτi p1 i . 0 Using the inequality of means [9, p. 15] ! r1 ! Ω1 n n n X Y 1 i ≤ wi sri sw i Ωn i=1 i=1 for r > 0, we deduce that n Y i=1 Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents " ir sw ≤ i 1 Ωn n X # Ωn wi sri i=1 for r > 0. According to above inequality, we have " # Ωn n n Y X 1 1 (ki ) (α +1)/(qi ωi ) ωi si i ui (si ) ≤ Qn 1 Ω qi n i=1 i=1 i=1 (αi + 1) p1 n Z si Y i βi pi × (si − τi ) Φi (τi ) dτi i=1 0 JJ J II I Go Back Close Quit Page 7 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au for r = (αi + 1)/qi ωi . In the following estimate we apply Hölder’s inequality and, at the end, change the order of integration: Qn (ki ) Z x1 Z xn i=1 ui si ··· iΩn ds1 · · · dsn h P (αi +1)/(qi ωi ) n 1 0 0 i=1 ωi si Ωn " Z Z # p1 n xi si Y i 1 ≤Q (si − τi )βi Φi (τi )pi dτi , dsi 1 n qi 0 0 (α + 1) i=1 i i=1 Z xi Z si p1 n 1 Y i 1 qi βi pi ≤Q xi (si − τi ) Φi (τi ) dτi , dsi 1 n qi 0 0 i=1 i=1 (αi + 1) p1 n n Z xi 1 Y Y i 1 qi βi +1 pi xi (xi − si ) Φi (si ) dsi . =Q 1 1 n qi pi 0 i=1 i=1 [(αi + 1) (βi + 1) ] i=1 This proves the theorem. Remark 2.1. In Theorem 2.1, setting Ωn = 1, we have Theorem 1.1. Corollary 2.2. Under the assumptions of Theorem 2.1, if r > 0, we have Qn (ki ) Z x1 Z xn i=1 ui si ··· h P iΩn ds1 · · · dsn (αi +1)/(qi ωi ) n 1 0 0 ω s i=1 i i Ωn 1 " n Z xi r # r·p n 1 Y X 1 1 q ≤ p r·p V xi i (xi − si )βi +1 Φi spi i dsi , p i 0 i=1 i=1 Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents JJ J II I Go Back Close Quit Page 8 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au where V is defined by (2.3). Proof. By the inequality of means, for any Ai ≥ 0 and r > 0, we obtain 1 # r·p " n n 1 X Y 1 r p Ai i ≤ p A . p i i=1 i=1 i The corollary then follows from the preceding theorem. Pn Lemma 2.3. Let γ1 > 0 and γ2 < −1. Let ωi > 0, i=1 ωi = Ωn and let si > 0, i = 1, . . . , n be real numbers. Then " #−γ1 Ωn n n Y X 1 2 sωi i γ1 γ2 ≥ ωi s−γ . i Ω n i=1 i=1 Proof. By the inequality of means, for any γ1 > 0 and γ2 < −1, we have " # γ1 γ2 Ω n n n Y X 1 sωi i γ1 γ2 ≥ ωi si . Ω n i=1 i=1 − 1 Using the fact that x γ2 is concave and using the Jensen inequality, we have that " # γ1 γ2 Ωn " # γ1 γ2 Ωn n n 1 X 1 X 2 ωi si = ωi f (s−γ ) i Ωn i=1 Ωn i=1 " !#γ1 γ2 Ωn n 1 X −γ2 ωi si ≥ f Ωn i=1 Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents JJ J II I Go Back Close Quit Page 9 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au = 1 Ωn n X !− γ1 γ1 γ2 Ωn 2 2 ωi s−γ i i=1 " n 1 X 2 = ωi s−γ i Ωn i=1 #−γ1 Ωn . The proof of the lemma is complete. Theorem 2.4. Under the assumptions of Theorem 2.1, if γ2 < −1, then Qn (ki ) Z x1 Z xn u (s ) i i i=1 ··· i−(αi +1)Ωn /γ2 qi ωi ds1 · · · dsn h P n −γ2 1 0 0 i=1 ωi si Ωn p1 n Z xi n 1 Y Y i qi βi +1 pi (xi − si ) Φi (si ) dsi , ≤V xi i=1 i=1 0 where V is given by (2.3). Proof. Using the inequality of Lemma 2.3, for any γ1 > 0 and γ2 < −1, we get #− γ1γΩn " n n 2 Y X 1 2 ωi s−γ sωi i γ1 ≤ . i Ω n i=1 i=1 According to above inequality, we deduce that #−W1 " n n X Y 1 1 (ki ) 2 ωi s−γ ui (si ) ≤ Qn 1 i (αi + 1) qi Ωn i=1 i=1 i=1 Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents JJ J II I Go Back Close Quit Page 10 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au × "Z n Y i=1 # p1 (si ) i (si − τi )βi Φi (τi )pi dτi , 0 where W1 = (αi + 1)Ωn /γ2 qi ωi . The proof of the theorem then follows from the preceding Theorem 2.1. Corollary 2.5. Under the assumptions of Theorem 2.4, if r > 0, we have Z x1 Z ··· 0 0 Qn (ki ) u (s ) i i i=1 i−(αi +1)Ωn /γ2 qi ωi ds1 · · · dsn h P n −γ2 1 i=1 ωi si Ωn 1 " n Z xi r # r·p n 1 Y X 1 1 q , ≤ p r·p V xi i (xi − si )βi +1 Φi (si )pi dsi p i 0 i=1 i=1 xn Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents where V is given by (2.3). Proof. By the inequality of means, for any Ai ≥ 0 and r > 0, we obtain n Y i=1 1 pi Ai " n X 1 r ≤ p Ai p i i=1 1 # r·p JJ J II I Go Back . The corollary then follows from the preceding Theorem 2.4. Close Quit Page 11 of 19 In the following section we discuss some choice of the functions Φi . J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au 3. The Various Inequalities (j) Theorem 3.1. Let ui ∈ C mi ([0, xi ]) be such that ui (0) = 0 for j ∈ {0, . . . , mi − 1}, i ∈ I. Then Z x1 Z ··· (3.1) 0 0 xn Qn (ki ) u (s ) i i=1 i iΩn ds1 · · · dsn h P (αi +1)/(qi ωi ) n 1 i=1 ωi si Ωn p1 n n Z xi pi 1 Y Y i qi βi +1 (mi ) ≤ V1 xi (xi − si ) , ui (si ) dsi i=1 i=1 Hilbert-Pachpatte Type Integral Inequalities and their Improvement 0 S.S. Dragomir and Young-Ho Kim where (3.2) V1 = Q h n i=1 1 1 qi (mi − ki − 1)!(αi + 1) (βi + 1) Proof. Inequality (3.1) is proved when we set (mi ) ui (si ) Φi (si ) = (mi − ki − 1)! in Theorem 2.1. 1 pi i. Title Page Contents JJ J II I Go Back Close Quit Page 12 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au Corollary 3.2. Under the assumptions of Theorem 3.1, if r > 0, we have Qn (ki ) Z x1 Z xn u (s ) i i=1 i ··· h P iΩn ds1 · · · dsn (αi +1)/(qi ωi ) n 1 0 0 ω s i=1 i i Ωn 1 " n Z xi r # r·p n pi 1 Y X 1 1 (m ) q ≤ p r·p V1 xi i (xi − si )βi +1 ui i (si ) dsi , p i 0 i=1 i=1 Hilbert-Pachpatte Type Integral Inequalities and their Improvement where V1 is given by (3.2). Theorem 3.3. Under the assumptions of Theorem 3.1, if γ2 < −1, then Qn (ki ) Z x1 Z xn i=1 ui (si ) (3.3) ··· h P i−(αi +1)Ωn /γ2 qi ωi ds1 · · · dsn n −γ2 1 0 0 ω s i=1 i i Ωn p1 n n Z xi pi 1 Y Y i (m ) qi ≤ V1 xi (xi − si )βi +1 ui i (si ) dsi , i=1 i=1 0 where V1 is given by (3.2). Proof. Inequality (3.3) is proved when we set (mi ) ui (si ) Φi (si ) = (mi − ki − 1)! in Theorem 2.4. S.S. Dragomir and Young-Ho Kim Title Page Contents JJ J II I Go Back Close Quit Page 13 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au Corollary 3.4. Under the assumptions of Theorem 3.3, if r > 0, we have Z x1 0 Qn (ki ) u (s ) i i i=1 ··· h P i−(αi +1)Ωn /γ2 qi ωi ds1 · · · dsn n −γ2 1 0 i=1 ωi si Ωn 1 " n Z xi r # r·p n pi 1 Y X 1 1 (m ) q ≤ p r·p V1 xi i (xi − si )βi +1 ui i (si ) dsi . p i 0 i=1 i=1 xn Z We discuss a number of special cases of Theorem 3.1. Similar examples apply also to Corollary 3.2, Theorem 3.3 and Corollary 3.4. Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Example 3.1. If ai = 0 and bi = 1 for i ∈ I, then Theorem 3.1 becomes Z x1 ··· 0 0 Title Page Qn (ki ) i=1 ui (si ) xn Z h 1 Ωn (qi mi −qi ki −qi +1)/(qi ωi ) i=1 ωi si Pn ≤ V2 n Y i=1 1 qi xi n Z Y 0 i=1 xi Contents iΩn ds1 · · · dsn 1 pi pi (mi ) (xi − si ) ui (si ) dsi , JJ J II I Go Back Close where V2 = Q h n i=1 1 1 (mi − ki − 1)!(qi mi − qi ki − qi + 1) qi i. Quit Page 14 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au Example 3.2. If ai = 0, bi = 1, qi = n, pi = n/(n − 1), mi = m and ki = k for i ∈ I, then Qn (ki ) Z x1 Z xn u (s ) i i i=1 ··· h P iΩn ds1 · · · dsn (nm−nk−n+1)/(nωi ) n 1 0 0 i=1 ωi si Ωn √ n x1 · · · xn n ≤ (m − k − 1)! (nm − nk − n + 1) n−1 n Z xi n Y n (m) n−1 dsi . × (xi − si ) ui (si ) 0 i=1 For q = p = n = 2 and ωi = n1 this is [12, Theorem 1]. Setting q = p = 2, k = 0, n = 1 and ωi = n1 , we recover the result of [14]. Example 3.3. If ai = 0 and bi = 1 for i ∈ I, then Theorem 3.1 becomes Qn (ki ) Z x1 Z xn u (s ) i i i=1 ··· h P iΩn ds1 · · · dsn (mi −ki )/(qi ωi ) n 1 0 0 i=1 ωi si Ωn p1 n n Z xi pi 1 Y Y i qi mi −ki (mi ) ≤ V3 xi (xi − si ) , ui (si ) dsi i=1 where i=1 0 1 . V3 = Qn i=1 (mi − ki )! Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents JJ J II I Go Back Close Quit Page 15 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au Example 3.4. If ai = 1, bi = 0, qi = n, pi = n/(n − 1), mi = m and ki = k for i ∈ I. Then (3.1) becomes Qn (ki ) x1 xn i=1 ui (si ) ··· iΩn ds1 · · · dsn h P (m−k)/(nωi ) n 1 0 0 ω s i=1 i i Ωn (n−1) √ n Z xi n/(n−1) n n x1 · · · xn Y m−k (m) n ≤ (xi − si ) dsi . ui (si ) (m − k)! i=1 0 Z Z Example 3.5. Let p1 , p2 ∈ R+ . If we set n = 2, ω1 = p11 , ω2 = p12 , mi = 1 and ki = 0 for i = 1, 2 in Theorem 3.1, then by our assumptions q1 = p1 /(p1 − 1), q2 = p2 /(p2 − 1), and we obtain Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Z 0 x1 Z 0 x2 |u1 (s1 )| |u2 (s2 )| h 1 p1 p2 Ω2 (p −1) p 2 s1 1 + (p −1)/p1 (p2 −1)/p2 x2 ≤ x1 1 (p −1) p 1 s2 2 Z x1 Contents iΩ2 ds1 ds2 p1 (x1 − s1 ) |u01 (s1 )| JJ J p1 1 ds1 0 Z × x2 p2 (x2 − s2 ) |u02 (s2 )| Go Back p1 ds2 2 II I . 0 If we set ω1 + ω2 = 1 in Example 3.5, then we have [13, Theorem 2]. (The values of ai and bi are irrelevant.) Close Quit Page 16 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au References [1] BICHENG YANG, On Hilbert’s integral inequality, J. Math. Anal. Appl., 220 (1988), 778–785. [2] G.D. HANDLEY, J.J. KOLIHA AND PEČARIĆ, New Hilbert-Pachpatte type integral inequalities, J. Math. Anal. Appl., 257 (2001), 238–250. [3] G.H. HARDY, J.E. LITTLEWOOD bridge Univ. Press, London, 1952. AND G. POLYA, Inequalities, Cam- [4] YOUNG-HO KIM, Refinements and Extensions of an inequality, J. Math. Anal. Appl., 245 (2000), 628–632. [5] V. LEVIN, On the two-parameter extension and analogue of Hilbert’s inequality, J. London Math. Soc., 11 (1936), 119–124. [6] G. MINGZE, On Hilbert’s inequality and its applications, J. Math. Anal. Appl., 212 (1997), 316–323. [7] D.S. MITRINOVIĆ, Analytic inequalities, Springer-Verlag, Berlin, New York, 1970. Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents JJ J II I [8] D.S. MITRINOVIĆ AND J.E. PEČARIĆ, On inequalities of Hilbert and Widder, Proc. Edinburgh Math. Soc., 34 (1991), 411–414. Go Back [9] D.S. MITRINOVIĆ, J.E. PEČARIĆ AND A.M. FINK, Classical and New Inequalities in Analysis, Kluwer Academic, Dordrecht, 1993. Quit [10] B.G. PACHPATTE, A note on Hilbert type inequality, Tamkang J. Math., 29 (1998), 293–298. Close Page 17 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au [11] B.G. PACHPATTE, On some new inequalities similar to Hilbert’s inequality, J. Math. Anal. Appl., 226 (1998), 166–179. [12] B.G. PACHPATTE, Inequalities similar to the integral analogue of Hilbert’s Inequality, Tamkang J. Math., 30 (1999), 139–146. [13] B.G. PACHPATTE, Inequalities similar to certain extensions of Hilbert’s inequality, J. Math. Anal. Appl., 243 (2000), 217–227. [14] B.G. PACHPATTE, A note on inequality of Hilbert type, Demonstratio Math., in press. [15] D.V. WIDDER, An inequality related to one of Hilbert’s, J. London Math. Soc., 4 (1929), 194–198. Hilbert-Pachpatte Type Integral Inequalities and their Improvement S.S. Dragomir and Young-Ho Kim Title Page Contents JJ J II I Go Back Close Quit Page 18 of 19 J. Ineq. Pure and Appl. Math. 4(1) Art. 16, 2003 http://jipam.vu.edu.au