Hindawi Publishing Corporation Journal of Inequalities and Applications Volume 2010, Article ID 430512, 18 pages doi:10.1155/2010/430512 Research Article A Note on the Integral Inequalities with Two Dependent Limits Allaberen Ashyralyev,1, 2 Emine Misirli,3 and Ozlem Mogol3 1 Department of Mathematics, Fatih University, Buyukcekmece, 34500 Istanbul, Turkey Department of Mathematics, ITTU, 74200 Ashgabat, Turkmenistan 3 Department of Mathematics, Ege University, 35100 Bornova-Izmir, Turkey 2 Correspondence should be addressed to Emine Misirli, emine.misirli@gmail.com Received 4 October 2009; Revised 28 April 2010; Accepted 5 July 2010 Academic Editor: Martin Bohner Copyright q 2010 Allaberen Ashyralyev et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The theorem on the Gronwall’s type integral inequalities with two dependent limits is established. In application, the boundedness of the solutions of nonlinear differential equations is presented. 1. Introduction Integral inequalities play a significant role in the study of qualitative properties of solutions of integral, differential and integro-differential equations see, e.g., 1–4 and the references given therein. One of the most useful inequalities in the development of the theory of differential equations is given in the following lemma see 5. Lemma 1.1. Let ut and ft be real-valued nonnegative continuous functions for all t ≥ 0. If u2 t ≤ c2 2 t fsusds 1.1 0 for all t ≥ 0, where c ≥ 0 is a real constant, then ut ≤ c t fsds 0 for all t ≥ 0. 1.2 2 Journal of Inequalities and Applications Note that the generalization of this integral inequality and its discrete analogies are given in papers 5–8. In paper 9 the following useful inequality with two dependent limits was established. Lemma 1.2. Let ut be a real-valued nonnegative continuous function defined on −T, T and let c and a be nonnegative constants. Then the inequality ut ≤ c sgnt t −t ausds, −T ≤ t ≤ T 1.3 implies that ut ≤ ce2a|t| , −T ≤ t ≤ T. 1.4 The theory of integral inequalities with several dependent limits and its applications to differential equations has been investigated in 10–14. The present study involves some Gronwall’s type integral inequalities with two dependent limits. Section 2 includes some new integral inequalities with two dependent limits and relevant proofs. Subsequently, Section 3 includes an application on the boundedness of the solutions of nonlinear differential equations. 2. A Main Statement Our main statement is given by the following theorem. Theorem 2.1. Let ut, at, bt, gt, ht, and mt be real-valued nonnegative continuous functions defined on R −∞, ∞. (i) Let c be a nonnegative constant. If u2 t ≤ c2 2 sgnt t −t msusds 2.1 msds 2.2 for t ∈ R, then ut ≤ c sgnt t −t for all t ∈ R. (ii) Let p > 1 be a real constant. If u t ≤ at bt sgnt p t −t gsup s hsus ds 2.3 Journal of Inequalities and Applications 3 for t ∈ R, then ut ≤ 1 at bt exp sgnt br gr hr dr p −t t t p−1 1 hs × sgnt as gs hs p p −t s 1/p 1 × exp − sgns br gr hr dr ds p −s 2.4 for all t ∈ R. (iii) Let ct be a real-valued positive continuous and nondecreasing function defined on R and p > 1 be a real constant. If up t ≤ cp t bt sgnt t −t gsup s hsus ds 2.5 for t ∈ R, then t c1−p r ut ≤ ct 1 bt exp sgnt br gr hr p −t dr t gs hsc1−p s × sgnt 2.6 −t s c1−p r × exp − sgns br gr hr p −s 1/p dr ds for all t ∈ R. (iv) Let kt, s and its partial derivative ∂kt, s/∂t be real-valued nonnegative continuous functions on −∞ < s ≤ t < ∞ and let kt, s be even function in t. If u t ≤ at bt sgnt p t −t kt, s gsup s hsus ds for t ∈ R, then ut ≤ 1 at bt exp sgnt kr, rbr gr hr dr p −t s t p−1 ∂ 1 ks, r ar gr hr hr dr × sgnt sgns p p 0 −s ∂s s 1 × exp − sgns kr, rbr gr hr dr p −s t 2.7 4 × exp sgnt t r sgnr s t −r Journal of Inequalities and Applications ∂ 1 k r, y b y g y h y dy dr ds ∂r p s 1 sgnt ks, s exp − sgns kr, rbr gr hr dr p −t −s 1/p p−1 1 × as gs hs hs Bk t, sds . p p 2.8 for all t ∈ R. Here Bk t, s ⎧ ⎪ ⎨Bk t, s, t ≥ 0, s ∈ R, ⎪ ⎩Bk− t, s, t ≤ 0, s ∈ R, 2.9 where t r ⎧ ⎪ ∂ ⎪ ⎪ k r, y B y dy dr , exp ⎪ ⎪ ⎨ s −r ∂r Bk− t, s t r ⎪ ⎪ ∂ ⎪ ⎪exp ⎪ k r, y B y dy dr , ⎩ −s −r ∂r t r ⎧ ⎪ ∂ ⎪ ⎪ k r, y B y dy dr , exp ⎪ ⎪ ⎨ s −r ∂r Bk t, s t r ⎪ ⎪ ∂ ⎪ ⎪ ⎪ k r, y B y dy dr , ⎩exp −s −r ∂r t ≤ s ≤ 0, 2.10 0 ≤ s ≤ −t, 0 ≤ s ≤ t, 2.11 −t ≤ s ≤ 0. Proof. i Define a function vt by vt c2 2 sgnt t −t msusds. 2.12 Note that vt is a nonnegative function and v0 c2 . Then 2.1 can be rewritten as u2 t ≤ vt, It is easy to see that vt is an even function. ut ≤ vt. 2.13 Journal of Inequalities and Applications 5 First, let t ≥ 0; then 2.12 can be rewritten as vt c 2 2 t −t 2.14 msusds. Differentiating 2.14 and using 2.13, we get v t ≤ 2mt vt 2m−t vt. 2.15 Dividing both sides of 2.15 by 2 vt, we get v t ≤ mt m−t. 2 vt 2.16 Integrating the last inequality from 0 to t, we get vt ≤ c t msds 0 t m−sds c sgnt 0 t −t msds. 2.17 Second, let t ≤ 0. Then, 2.12 can be written as vt c2 − 2 t −t 2.18 msusds. Differentiating 2.18 and using 2.13, we get −v t ≤ 2mt vt 2m−t vt. 2.19 Dividing both sides of 2.19 by 2 vt, we get v t − ≤ mt m−t. 2 vt 2.20 Integrating 2.20 from t to 0, we get vt ≤ c 0 t msds 0 t m−sds c sgnt t −t msds. 2.21 6 Journal of Inequalities and Applications Finally, using 2.17 and 2.21, we obtain t vt ≤ c sgnt msds. −t 2.22 The inequality 2.2 follows from 2.13 and 2.22. ii Define a function vt by vt sgnt t −t gsup s hsus ds. 2.23 It is evident that vt is an even and nonnegative function. We have that up t ≤ at btvt, ut ≤ at btvt1/p . 2.24 Using Young’s inequality see, e.g., 2, we obtain that at btvt p − 1 . p p ut ≤ 2.25 Let t ≥ 0. Then vt t −t gsup s hsusds. 2.26 Differentiating 2.26, we get v t gtup t htut g−tup −t h−tu−t. 2.27 Using 2.24 and 2.25, we get 1 1 v t ≤ vt bt gt ht b−t g−t h−t p p p−1 1 1 at gt ht a−t g−t h−t ht h−t. p p p 2.28 Denoting 1 Bt bt gt ht , p p−1 1 At at gt ht ht, p p 2.29 we get v t − vtBt B−t ≤ At A−t. 2.30 Journal of Inequalities and Applications 7 From that it follows that t exp Br B−rdr v s − vsBs B−s s ≤ exp t 2.31 Br B−rdr As A−s s for any s ≤ t. Integrating the last inequality from 0 to t and using v0 0, we get vt ≤ t t As A−s exp 0 Br B−rdr ds. 2.32 s It is easy to see that t Br B−rdr t −t s Brdr − s −s 2.33 Brdr. Then t vt ≤ exp t −t Brdr s Brdr ds. As A−s exp − 2.34 −s 0 Since 0 ≤ s ≤ t, we have that vt ≤ exp sgnt × t t −t Brdr 0 s −s As exp − Brdr ds As exp − Brdr ds −s 0 exp sgnt × t −t −t Brdr As exp − sgns 0 exp sgnt s t −s Brdr ds t −t s Brdr t sgnt −t 0 −t As exp − sgns As exp − sgns s −s s −s Brdr ds Brdr . 2.35 8 Journal of Inequalities and Applications Applying 2.24, we obtain ut ≤ at bt exp sgnt × sgnt t −t t −t Brdr s 1/p As exp − sgns Brdr ds . 2.36 −s From 2.36, and 2.29 it follows 2.4 for t ≥ 0. Let t ≤ 0; then vt − t −t gsup s hsus ds, 2.37 −v t gtu t htut g−tu −t h−tu−t. p p Using 2.24 and 2.25, we get −v t ≤ vtBt B−t At A−t. 2.38 From that it follows that − exp s Br B−rdr t ≤ exp s v s vsBs B−s 2.39 Br B−rdr As A−s t for any t ≤ s. Integrating the last inequality from t to 0 and using v0 0, we get vt ≤ 0 As A−s exp s t Br B−rdr ds. 2.40 t It is easy to see that s Br B−rdr t −t t Brdr − −s Brdr. 2.41 s Then −t vt ≤ exp 0 Brdr t t −s Brdr ds. As A−s exp − s 2.42 Journal of Inequalities and Applications 9 Since t ≤ s ≤ 0, we have that vt ≤ exp sgnt exp sgnt × 0 −t t −t s t Brdr −s t exp sgnt × Brdr −s Brdr ds As A−s exp − 0 s s As exp Brdr ds A−s exp Brdr ds 0 0 t −t −s t t 2.43 Brdr −t s −s As exp Brdr ds As exp Brdr ds −s t exp sgnt exp sgnt t −t Brdr As exp − sgns Brdr s t t −t 0 −t t sgnt −t s −s Brdrds s As exp − sgns Brdr ds. −s Applying 2.43 and 2.24, we obtain 2.36 for t ≤ 0. Then from 2.36 and 2.29, 2.4 follows for t ≤ 0. iii Since ct is a positive, continuous, and nondecreasing function for t ∈ R, we have that ut ct p ≤ 1 bt sgnt t −t us us p 1−p ds. hsc s gs cs cs 2.44 Now the application of the inequality proven in ii yields the desired result in 2.6. iv We define a function vt by vt sgnt t −t kt, s gsup s hsus ds. 2.45 Evidently, the function vt is a nonnegative, monotonic, and nondecreasing in t and v0 0. We have that up t ≤ at btvt, ut ≤ at btvt1/p . 2.46 10 Journal of Inequalities and Applications Let t ≥ 0. Then vt t −t kt, s gsup s hsus ds. 2.47 Differentiating 2.47, we get v t kt, t gtup t htut kt, −t g−tup −t h−tu−t t ∂ kt, s gsup s hsus ds. −t ∂t 2.48 Using 2.46 and Young’s inequality, we obtain that 1 1 v t ≤ vt kt, tbt gt ht kt, −tb−t g−t h−t p p t 1 ∂ kt, sbs gs hs ds p −t ∂t p−1 1 kt, t gtat ht at p p p−1 1 kt, −t g−ta−t h−t a−t p p t p−1 1 ∂ kt, s gsas hs as ds. p p −t ∂t 2.49 Using 2.29, we get v t ≤ vt kt, tBt kt, −tB−t kt, tAt kt, −tA−t t −t t −t ∂ kt, sBsds ∂t 2.50 ∂ kt, sAsds. ∂t Applying the differential inequality, we get vt ≤ t s ∂ ks, rArdr ks, sAs ks, −sA−s 0 −s ∂s t r ∂ × exp k r, y B y dy dr . kr, rBr kr, −rB−r s −r ∂r 2.51 Journal of Inequalities and Applications 11 Since kt, s k−t, s, we have that vt ≤ t s ∂ ks, rArdr 0 −s ∂s t r ∂ × exp k r, y B y dy dr ds. kr, rBr k−r, −rB−r s −r ∂r ks, sAs k−s, −sA−s 2.52 Using 2.33, we get vt ≤ exp × t −t kr, rBrdr t s −s 0 ∂ ks, rArdr ∂s s × exp − −s kr, rBrdr t r s −r ∂ k r, y B y dy dr ds ∂r s t r ∂ ks, sAs exp − k r, y B y dy dr ds kr, rBrdr 0 −s s −r ∂r s t t r ∂ k−s, −sA−s exp − k r, y B y dy dr ds . kr, rBrdr ds 0 −s s −r ∂r 2.53 t Since 0 ≤ s ≤ t, we have that vt ≤ exp sgnt × sgnt t −t kr, rBrdr s t sgns 0 −s ∂ ks, rArdr ∂s s t r ∂ × exp − k r, y B y dy dr ds kr, rBrdr −s s −r ∂r s t t r ∂ ks, sAs exp − k r, y B y dy dr ds kr, rBrdr 0 −s s −r ∂r −s 0 t r ∂ k r, y B y dy dr ds . ks, sAs exp − kr, rBrdr −t s −s −r ∂r 2.54 12 Journal of Inequalities and Applications Using 2.9 and 2.11, we get vt ≤ exp sgnt × sgnt t −t kr, rBrdr t s sgns −s 0 × exp − sgns t ∂ ks, rArdr ∂s s −s kr, rBrdr sgnt r sgnr s −r ∂ k r, y B y dy dr ds ∂r s ks, sAs exp − sgns kr, rBrdr Bk t, sds −s 0 t 0 −t s ks, sAs exp − sgns kr, rBrdr Bk t, sds −s exp sgnt × sgnt t −t kr, rBrdr t s sgns 0 × exp − sgns sgnt 0 −t −s ∂ ks, rArdr ∂s s −s kr, rBrdr sgnt t r sgnr s −r ∂ k r, y B y dy dr ds ∂r s ks, s exp − sgns kr, rBrdr AsBk t, sds . −s 2.55 Let t ≤ 0. Then vt − t −t kt, s gsup s hsus ds. 2.56 Differentiating 2.56, we get −v t kt, t gtup t htut kt, −t g−tup −t h−tu−t t −t ∂ kt, s gsup s hsus ds. ∂t 2.57 Journal of Inequalities and Applications 13 Using 2.46 and Young’s inequality, we obtain that 1 1 −v t ≤ vt kt, tbt gt ht kt, −tb−t g−t h−t p p t −t 1 ∂ kt, sbs gs hs ds ∂t p p−1 1 at kt, t gtat ht p p 2.58 p−1 1 kt, −t g−ta−t h−t a−t p p −t t p−1 1 ∂ kt, s gsas hs hs ds. ∂t p p Using 2.29, we get −v t ≤ vt kt, tBt kt, −tB−t −t t kt, tAt kt, −tA−t −t t ∂ kt, sBsds ∂t 2.59 ∂ kt, sAsds. ∂t Applying the differential inequality, we get 0 −s ∂ ks, rArdr vt ≤ ks, sAs ks, −sA−s t s ∂s × exp s kr, rBr kr, −rB−r t −r r ∂ k r, y B y dy dr ds. ∂r 2.60 Since kt, s k−t, s, we have that vt ≤ 0 t ks, sAs k−s, −sA−s −s s ∂ ks, rArdr ∂s −r s ∂ × exp k r, y B y dy dr ds. kr, rBr k−r, −rB−r t r ∂r 2.61 14 Journal of Inequalities and Applications Using 2.41, we get −t vt ≤ exp kr, rBrdr t × 0 −s ∂ ks, rArdr t s ∂s s −r −s ∂ k r, y B y dy dr ds kr, rBrdr × exp − s t r ∂r 0 s −r −s ∂ ks, sAs exp − k r, y B y dy dr ds kr, rBrdr t s t r ∂r 0 s −r −s ∂ k−s, −sA−s exp − k r, y B y dy dr ds . kr, rBrdr ds t s t r ∂r 2.62 Since t ≤ s ≤ 0, we have that t vt ≤ exp sgnt t −t kr, rBrdr s ∂ ks, rArdr ∂s 0 −s s −r s ∂ k r, y B y dy dr ds kr, rBrdr × exp − sgns −s t r ∂r 0 s −r −s ∂ ks, sAs exp − k r, y B y dy dr ds kr, rBrdr t s t r ∂r −t −s −r s ∂ k r, y B y dy dr ds . ks, sAs exp − kr, rBrdr 0 −s t r ∂r 2.63 × sgnt sgns Using 2.9 and 2.10, we get t vt ≤ exp sgnt × sgnt t −t kr, rBrdr s sgns 0 × exp − sgns 0 t −s ∂ ks, rArdr ∂s s −s kr, rBrdr sgnt t r sgnr s −r ∂ k r, y B y dy dr ds ∂r s ks, sAs exp − sgns kr, rBrdr Bk− t, sds −t 0 ks, sAs exp − sgns −s s −s kr, rBrdr Bk− t, sds Journal of Inequalities and Applications t exp sgnt × sgnt −t 15 kr, rBrdr s t sgns −s 0 ∂ ks, rArdr ∂s × exp − sgns s −s kr, rBrdr sgnt t sgnr s r ∂ k r, y B y dy dr ds −r ∂r −t s sgnt ks, s exp − sgns kr, rBrdr AsBk t, sds . × −s 0 2.64 The inequality 2.8 follows from 2.29, 2.55, and 2.64. Theorem 2.1 is proved. 3. An Application In this section, we indicate an application of Theorem 2.1 part ii to obtain the explicit bound on the solution of the following boundary value problem for one dimensional partial differential equations: p p vtt t, x − axvx t, x δvp t, x Ft, x; vt, x, x vx t, 0 vx t, l, vt, 0 vt, l, v0, x ϕx, vt 0, x ψx, t ∈ R, 0 < x < l, 3.1 t ∈ R, 0 ≤ x ≤ l, where p > 1 is a fixed real number and δ const > 0. Let Ft, x; vt, x, t ∈ R, x ∈ 0, l, ax ≥ a > 0, x ∈ 0, l, ϕx, ψx, x ∈ 0, l be smooth functions and problem 3.1 has a unique smooth solution vt, x. Assume that l 1/2 l ≤ gt F t, x; vt, xdx 2 0 1/2 ht v t, xdx 2p 0 l 1/2 v t, xdx 2 3.2 0 for all t ∈ R. Here gt and ht are real-valued nonnegative continuous functions defined on R. This allows us to reduce the nonlocal boundary-value 3.1 to the initial-value problem p vtt t Avp t Ft, vt, v0 ϕ, t ∈ R, vt 0 ψ 3.3 16 Journal of Inequalities and Applications in a Hilbert space H L2 0, l with a self-adjoint positive definite operator A defined by the formula Aux −axux xx δux, with the domain DA {ux : u x ∈ L2 0, l, u0 ul, u 0 u l} see, e.g., 15, 16. Let us give a corollary of Theorem 2.1. Theorem 3.1. The solution of problem 3.1 satisfies the estimates l 1/2p v t, xdx 2p ≤ 0 t 1 1 1 1−1/p M √ exp sgnt hr dr √ gr l p δ δ −t × sgnt t −t p − 1 1−1/p 1 1−1/p l hs hs M gs l p p 3.4 s 1/p 1 1 1−1/p hr dr ds × exp − sgns √ gr l p δ −s l l for all t ∈ R. Here M 0 ϕ2p xdx1/2 p/δ 0 ϕ2p−1 xψ 2 xdx1/2 . Proof. It is known thatthe formula see, e.g., 15, 16 vp t ctvp 0 stvp 0 t st − sFs, vsds 3.5 0 gives a solution of problem 3.3. Here ct eitA 1/2 e−itA 2 1/2 st A−1/2 , eitA 1/2 − e−itA 2i 1/2 . 3.6 Applying the triangle inequality, condition 3.2, formula 3.5, and estimates see, e.g., 17 ctH → H ≤ 1, 1/2 A st H →H ≤ 1, −1/2 A H →H 1 ≤√ , δ 3.7 we get v tH p 1 1 ≤ v 0H √ vp 0H √ δ δ p t 0 gsvp sH hsvsH ds. 3.8 Journal of Inequalities and Applications 17 Since 1 v 0H √ vp 0H δ p l 1/2 ϕ xdx 2p 0 l 1/2 p 2p−1 2 ϕ , xψ xdx δ 0 3.9 1/p vsH ≤ l1−1/p vp sH we have that 1 vp tH ≤ M √ sgnt δ t −t 1/p gsvp sH l1−1/p hsvp sH ds. 3.10 1/p Denote that ut vp tH . Then 1 u t ≤ M √ sgnt δ p t gsup s l1−1/p hsus ds −t 3.11 for t ∈ R. Applying the integral inequality 2.4, we get ut ≤ t 1 1 1 1−1/p M √ exp sgnt hr dr √ gr l p δ δ −t × sgnt t p − 1 1−1/p 1 l hs M gs l1−1/p hs p p −t 3.12 s 1/p 1 1 1−1/p hr dr ds . × exp − sgns √ gr l p δ −s We have that ut v p 1/p tH l 1/2p v t, xdx 2p . 3.13 0 Therefore, the inequality 3.4 follows from the last inequality. Theorem 3.1 is proved. Acknowledgments The authors thank professor O. 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