Applied Mathematics E-Notes, 16(2016), 21-32 c Available free at mirror sites of http://www.math.nthu.edu.tw/ amen/ ISSN 1607-2510 Existence Of Nontrivial Solutions For A p-Laplacian Problems With Impulsive E¤ects El Miloud Hssiniy, Mohammed Massarz, Lakhdar Elbouyahyaouix Received 11 January 2015 Abstract In this paper, we study a class of p-Laplacian problems with impulsive conditions depending on a real parameter . Using variational methods and Bonnano’s critical points theorem [4], we give some appropriate conditions on the nonlinear term and the impulsive functions to …nd a range of the control parameter for which the impulsive problem admits at least one nontrivial solution. 1 Introduction In this work, we study the existence of nontrivial solutions for the following p-Laplacian problem with the impulsive conditions 8 ( (x) p (u0 ))0 + s(x) p (u) = f (x; u(x)); a.e. x 2 (a; b); > > < 0 + 0 (1) 1 u (a ) 2 u(a) = 0; 1 u (b ) + 2 u(b) = 0; > > : ( (xj ) p (u0 (xj ))) = Ij (u(xj )); j = 1; 2; : : : ; n; where p (t) = jtjp 2 t and a; b 2 R with a < b, p > 1, 1 , 2 , 1 , 2 and are positive constants, ; s 2 L1 ([a; b]) with 0 := ess inf x2[a;b] (x) > 0, s0 := ess inf x2[a;b] s(x) > 0, (a+ ) = (a) > 0, (b ) = (b) > 0, f : [a; b] R ! R, Ij : R ! R are continuous for j = 1; : : : ; n, and x0 = a < x1 < x2 < < xn < xn+1 = b: We note that ( (xj ) 0 p (u (xj ))) = (x+ j ) 0 + p (u (xj )) (xj ) 0 p (u (xj )); where z(y + ) and z(y ) denote the right and left limits of z(y) at y respectively. The theory of impulsive di¤erential equations has become an important area of investigation in the past two decades because of their applications to various problems arising in communications, control technology, electrical engineering, population dynamics, biotechnology processes, chemistry and biology (see [2, 3, 8, 12, 14]). There have been many papers to study impulsive problems by variational method and critical point theory, we refer the reader to [13, 15, 20, 23] and references cited Mathematics Subject Classi…cations: 34B15, 34B18, 58E30. Mohamed I, Faculty of Sciences, Oujda, Morocco z University Mohamed I, Faculty of Sciences and Technics, Al Hoceima, Morocco x Regional Centre of Trades Education and Training, Taza, Morocco y University 21 22 Existence of Nontrivial Solution for a p-Laplacian Problems therein. In [19] Tian and Ge obtained su¢ cient conditions that guarantee the existence of at least two positive solutions of a p-Laplacian boundary value problem with impulsive e¤ects 8 0 0 > > ( (t) p (u (t))) + s(t) p (u(t)) = f (t; u(t)); a.e. t 2 (a; b); < u0 (a+ ) u(a) = A; u0 (b ) + u(b) = B; > > : ( (ti ) p (u0 (tj ))) = Ii (u(ti )); i = 1; 2; : : : ; l; where a; b 2 R with a < b, p > 1, p (t) = jtjp 2 t, ; s 2 L1 ([a; b]) with ess inf t2[a;b] (t) > 0, ess inf t2[a;b] s(t) > 0, 0 < (a); (b) < +1, A 0; B 0, , , , are positive constants, Ii 2 C([0; +1); [0; +1)) for i = 1; : : : ; l, f 2 C([a; b] [0; +1); [0; +1)), f (t; 0) 6= 0 for t 2 [a; b], t0 = a < t1 < t2 < tl < tl+1 = b. In [1], by virtue of Ricceri’s three critical points theorem [18], Bai and Dai studied the existence of at least three solutions for the following p-Laplacian impulsive problem 8 ( (t) p (u0 (t)))0 + s(t) p (u(t)) = f (t; u(t)); a.e. t 2 (a; b); > > < 0 + 0 1 u (a ) 2 u(a) = 0; 1 u (b ) + 2 u(b) = 0; > > : ( (ti ) p (u0 (tj ))) = Ii (u(ti )); i = 1; 2; : : : ; l: In [5], Bonnano et al. considered the second-order impulsive di¤erential equations with Dirichlet boundary conditions, depending on two real parameters 8 u00 (t) + a(t)u0 (t) + b(t)u(t) = g(t; u(t)); t 2 [0; T ] ; t 6= tj ; > > < u(0) = u(T ) = 0; > > : u0 (tj ) = u0 (t+ u0 (tj ) = Ij (u(tj )), j = 1; 2; :::; n; j ) where ; > 0, g : [0; T ] R ! R, a; b 2 L1 ([0; T ]) satisfy the conditions ess inf t2[0;T ] a(t) 0, ess inf t2[0;T ] b(t) 0, 0 = t0 < t1 < t2 < < tn < tn+1 = T , u0 (tj ) = 0 0 0 + 0 u (tj ) u (tj ) = limt!t+ u (t) limt!t u (t), and Ij : R ! R are continuous for every j j j = 1; 2; : : : ; n. Under an appropriate growth condition of the nonlinear function, and a small perturbations of impulsive terms, they established the existence of at least three solutions by choosing in a suitable way and for every lying in a precise interval. Recently, the authors in [10] studied the following nonlinear perturbed problem 8 0 0 > > ( (t) p (u (t))) + s(t) p (u(t)) = f (t; u(t)) + g(t; u(t)); a.e. t 2 (a; b); < 0 + 0 1 u (a ) 2 u(a) = 0; 1 u (b ) + 2 u(b) = 0; > > : ( (ti ) p (u0 (tj ))) = Ii (u(ti )); i = 1; 2; : : : ; l: They utilized Bonnano’s theorem [6], to establish precise values of and for which the above problem admits at least three weak solutions. Motivated by the above mentioned works, our goal in this paper is to obtain some su¢ cient conditions to guarantee that problem (1) admits at least one nontrivial solution when the parameter lies in di¤erent intervals. Our analysis is mainly based on the critical point theorems obtained by Bonanno [4]. This theorem has been used in several works to obtain existence results for di¤erent kinds of problems. For review on the subject, we refer the reader to [7, 9, 11]. Hssini et al. 2 23 Preliminaries Our main tools are two consequences of a local minimum theorem ([4], Theorem 3.1) which is a more general version of the Ricceri variational principle (see [17]). Given a set X and two functionals ; : X ! R; we put (r1 ; r2 ) := u2 supv2 inf 1 1 (]r r2 (]r1 ;r2 [) (u) 1 (r1 ; r2 ) := u2 1 (]r 1 (] (u) 1 ;r2 [) (u) ; (u) supv2 sup (v) 1 ;r2 [) 1;r1 [) (2) (v) ; r1 (3) and (u) (r) := sup supv2 (u) 1 (]r;+1[) u2 1 (] (v) 1;r[) (4) r for all r; r1 ; r2 2 R; with r1 < r2 . THEOREM 1 ([4], Theorem 5.1). Let X be a re‡exive real Banach space, : X ! R be a sequentially weakly lower semicontinuous, coercive and continuously Gateaux di¤erentiable function whose Gateaux derivative admits a continuous inverse on X , and : X ! R be a continuously Gateaux di¤erentiable function whose Gateaux derivative is compact. Put I = and assume that there are r1 ; r2 2 R; with r1 < r2 ; such that (r1 ; r2 ) < 1 (r1 ; r2 ); (5) i h 1 1 where ; 1 are given by (2) and (3). Then, for each 2 (r1 ;r2 ) ; (r1 ;r2 ) ; there 1 is a u0; 2 I 0 (u0; ) = 0: 1 (]r1 ; r2 [) such that I (u0; ) 1 I (u) for all u 2 (]r1 ; r2 [) and THEOREM 2 ([4], Theorem 5.3). Let X be a real Banach space; : X ! R be a continuously Gateaux di¤erentiable function whose Gateaux derivative admits a continuous inverse on X . : X ! R be a continuously Gateaux di¤erentiable function whose Gateaux derivative is compact. Fix inf X < r < supX and assume that (r) > 0; where is given by (4), and for each 1 ; there is a u0; 2 Then, for > (r) 1 u2 (]r; +1[) and I 0 (u0; ) = 0: (6) 1 > (r) the function I = 1 (]r; +1[) such that I (u0; ) Let X be the Sobolev space W 1;p ([a; b]) equipped with the norm kuk := Z a b 0 p (x) ju (x)j dx + Z a b p !1=p s(x)ju(x)j dx ; is coercive. I (u) for all 24 Existence of Nontrivial Solution for a p-Laplacian Problems which is equivalent to the usual one. We de…ne the norm in C 0 ([a; b]) as kuk1 = max ju(x)j: x2[a;b] Since p > 1, X is compactly embedded in C 0 ([a; b]). LEMMA 1 ([19], lemma 2.6). For u 2 X, we have kuk1 M kuk, where ( ) (b a) 1=p (b a)1=q 1 1 1=q ; M = 2 max ; + = 1: 1=p 1=p p q s0 0 Throughout the sequel, we assume that the functions f and Ij satisfy the following assumptions: (F) f : [a; b] R ! R is an L1 -Carathéodory function namely: t ! f (t; x) is measurable for every x 2 R, x ! f (t; x) is continuous for almost every t 2 [a; b], and for every % > 0 there exists a function l% 2 L1 ([a; b]) such that sup jf (x; ) l% (x) for a.e. x 2 [a; b]: j j % (H) The impulsive functions Ij have sublinear growth, i.e., there exist constants aj ; bj > 0 and j 2 [0; p 1) such that jIj (x)j aj + bj jxj j for all x 2 R; j = 1; 2; : : : ; n: DEFINITION 1. We say that u 2 X is a weak solution of problem (1) if, for v 2 X, Z b Z b 2 u(a) 0 0 (x) p (u (x))v (x)dx + s(x) p (u(x))v(x)dx + (a) p v(a) 1 a a 0 1 Z b n X 2 u(b) @ + (b) p v(b) Ij (u(xj ))v(xj )A = 0: f (x; u(x))v(x)dx a 1 Now, Put F (x; ) = Z 0 j=1 f (x; t)dt for all (x; ) 2 [a; b] R: We introduce the functional I : X ! R de…ned, for each u 2 X; by I (u) = where 8 > < > : (u) = p1 kukp + (u) = Rb a (u) (u); 1 (a) p p 2 1 ju(a)j p p 1 F (x; u)dx Pn + R u(xj ) j=1 0 1 (b) p p 2 1 ju(b)j ; p p 1 Ij (t)dt: (7) Hssini et al. 25 By the property of f and the continuity of Ij (j = 1; 2; :::; n); we have that and are well de…ned and Gâteaux di¤erentiable functionals, whose Gâteaux derivatives at u 2 X are given by Z b Z b 0 (u)v = (x) p (u0 (x))v 0 (x)dx + s(x) p (u(x))v(x)dx a a 2 u(a) + (a) p and 0 v(a) + (b) 1 (u)v = Z 2 u(b) v(b) p 1 b f (x; u)vdx a n X Ij (u(xj ))v(xj ) j=1 for all v 2 X: We need the following Proposition in the proofs of our main results. PROPOSITION 1 ([10], Proposition 2.4). Let T : X ! X be de…ned by Z b Z b 0 0 T (u)h = (x) p (u (x))h (x)dx + s(x) p (u(x))h(x)dx a a + (a) 2 u(a) p h(a) + (b) 1 2 u(b) h(b); p 1 for every u; h 2 X. Then the operator T admits a continuous inverse on X . 3 Main Results For the sake of convenience, we put k := and c := 2p (p n X aj + c j=1 2(p + 1) 0 + 1)jj jj1 + (p + 2)(b bj j +1 c j 1 and (8) a)p jjsjj1 (d) = 0d k(b Mp a)p 2=p p 1 ; where aj , bj , j are given by (H), M is given in Lemma 1 and c, d are two positive constants. Moreover, given a nonnegative constant and a positive constant such that ! p p (b) 2p 1 (a) 2p 1 0 (1 + C1 ) p + 6= ; where C1 = M : p 1 p 1 Mp k(b a)p 1 1 1 We set A ( ) := Rb a maxjtj F (x; t)dx + p Mp 2 + ( ) 0 (1 ( ) p + C1 ) k(b a)p 1 Rb a+b 2 F (t; ) dt : 26 Existence of Nontrivial Solution for a p-Laplacian Problems THEOREM 3. Assume that there exists a nonnegative constant constants 2 and with p 1 < 0M p p (b k (1 + C1 ) < a)p 1 1 and two positive p 2; (9) such that (A1) A ( 2 ) < A ( 1 ), [0; ]: 0 for every (x; t) 2 [a; a+b 2 ] i h Then, for each 2 p1 A (1 ) ; A (1 ) , problem (1) admits at least one nontrivial weak 1 2 solution u 2 X such that p p (A2) F (x; t) 1 pM p < (u) < 2 pM p : PROOF. Let and be the functionals de…ned in (7). It is well known that is coercive and sequentially weakly lower semicontinuous. From Proposition 1, of course, 0 admits a continuous inverse on X . Moreover, has a compact derivative, it results sequentially weakly continuous. Hence and satisfy all regularity assumptions requested in Theorem 1. So, our aim is to verify condition (5). To this end, let r1 = p 1 pM p ; r2 = p 2 pM p Clearly u0 2 X. Moreover, one has 2p p ku0 k = (b a)p p Z a+b 2 2p p (x)dx + (b a)p a 2 b a (x ; and u0 (x) = a); ; Z a+b 2 x 2 [a; a+b 2 [; x 2 [ a+b 2 ; b]: p (x a) s(x)dx + a p Z (10) b s(x)dx: a+b 2 Using (8), we observe that p p 0 (b From the de…nition of a)p 1 ku0 kp 0 k(b a)p 1 : (11) , we have 1 kukp p (u) 1 (1 + C1 ) kukp : p In particular, we infer p p 0 p(b a)p 1 (u0 ) (1 + C1 ) Hence, it follows from (9) that r1 < (u0 ) < r2 : 0 pk(b a)p 1 : (12) Hssini et al. 27 1 Now, let u 2 X such that u 2 (] 1; r2 [). By Lemma 1, we obtain ju(x)j 2 for each x 2 [a; b]: (13) Moreover, thanks to (H), we get n Z X j=1 n X u(tj ) Ij (x) dx 0 aj kuk1 + j=1 j bj kuk1j +1 ; +1 (14) which combined with (13) yields that sup u2 1 (] (u) = 0 Z @ sup 1;r2 [) 1 (] u2 Z F (x; u)dx a b j=1 max F (x; t)dx + a jtj Z 1;r2 [) 2 n X j=1 b 2 2 max F (x; t)dx + a jtj n Z X b u(xj ) 0 Ij (t)dtA bj kuk1j +1 + 1 j aj kuk1 + 2 1 : (15) 2 Arguing as before, we obtain sup 1 (] u2 (u) 1;r1 [) Z b max F (x; t)dx + a jtj 2 1 1 : (16) 1 On the other hand, due to Lemma 1, (H), (A2) and (11), we have Z (u0 ) Z Z b F (t; ) dt a+b 2 b F (t; ) dt a+b 2 n Z X j=1 n X j=1 b F (t; ) dt ( ) a+b 2 u0 (xj ) Ij (t)dt 0 aj ku0 k1 + j bj ku0 k1j +1 +1 ( ): (17) Therefore, from (12) and (15)–(17), we get supu2 (r1 ; r2 ) Rb a = 1 (]r 1 ;r2 [) r2 maxjtj pA ( 2 ): 2 (u) (u0 ) (u0 ) F (x; t)dx + p 2 pM p 2 2 2 + ( ) 0 (1 + C1 ) pk(b a)p ( ) p 1 Rb a+b 2 F (t; ) dt 28 Existence of Nontrivial Solution for a p-Laplacian Problems We also obtain (u0 ) supu2 1 (r1 ; r2 ) (u0 ) Rb a+b 2 = 1 (] F (t; ) dt r1 ( ) 2 1 ( ) 0 (1 + C1 ) pk(b a)p each that 2 1 A ( Rb a 1 p maxjtj 1 F (x; t)dx p 1 pM p 1 pA ( 1 ): So, by our assumption it follows that (r1 ; r2 ) < i h 1 p (u) 1;r1 [) ; 1 1) A ( 2) 1 (r1 ; r2 ): Hence, from Theorem 1 for ; the functional I admits at least one critical point u such p 1 pM p < (u) < p 2 pM p ; and the proof of Theorem 3 is achieved. Now, we point out the following consequence of Theorem 3. THEOREM 4. Assume that there exist two constants 0M (b p a)p 1 p < k (1 + C1 ) p and with ; such that assumption (A2) in Theorem 3 holds. Furthermore, suppose that Rb a maxjtj F (x; t)dx + 2 k(b a)p 1 < p 0 M (1 + C1 ) Rb a+b 2 F (t; ) dt ( ) ( ) : (18) problem (1) admits at least one nontrivial weak solution u such that ju(x)j < x 2 [a; b]: for all p p Then, for each 3 p p 15 0 M (1 + C1 ) 2 Rb p ( ) a+b F (t; ) dt 2 p ( ) ; Rb a maxjtj k(b a)p 1 F (x; t)dx + PROOF. Our aim is to apply Theorem 3. To this end we pick 1 2 2 4; = 0 and 2 = : Hssini et al. 29 From (18); one has A ( ) Rb a = h < maxjtj 0 M i hR p b M p (1+C1 ) p k(b a)p 1 a p M a = = + ( ) p 1 Rb 2 F (x; t)dx + maxjtj F (x; t)dx + p M Rb ( ) p a+b 2 0 (1 + C1 ) k(b a)p 1 maxjtj 2 F (x; t)dx + + C1 ) p k(b a)p 1 Rb 0 (1 2 a+b 2 < F (t; ) dt F (t; ) dt i ( ) ( ) p 0 (1 + C1 ) k(b a)p 1 A (0): Hence, Theorem 3 ensures the existence of nontrivial weak solution u of problem (1) such that p 1 kukp ; (u) < p pM p and clearly by Lemma 1, ju(x)j < for all x 2 [a; b]: Finally, we also give an application of Theorem 2. THEOREM 5. Assume that there exist two constants p such that Z < 0M (b 2 a jtj and < F (x; ) j jp j!+1 lim sup j Then, for each p Z with ; b F (x; )dx ( ) a+b 2 ( ); (19) 0 uniformly in x: (20) > ; where p = p a)p 1 b max F (x; t)dx + p and hR b a Mp maxjtj F (x; t)dx + 0 (1 p + C1 ) k(b a)p 1 2 + ( ) ( ) Rb a+b 2 i; F (x; )dx problem (1) admits at least one nontrivial weak solution u such that jjujj > M (1+C1 )1=p : PROOF. The functionals and given by (7) satisfy all regularity assumptions requested in Theorem 2. Moreover, by standard computations, condition (20) implies 30 Existence of Nontrivial Solution for a p-Laplacian Problems that I ; > 0; is coercive. To apply Theorem 2, it su¢ ces to verify condition (6). p Indeed, put u0 (x) as in (10) and r = pM p : Arguing as in the proof of Theorem 3 we obtain (u) (r) Rb a+b 2 supv2 (u) F (t; ) dt 1 (] 1;r[) (v) r ( ) 0 (1 ( ) + C1 ) pk(b a)p 2 Rb a p maxjtj F (x; t)dx : p 1 pM p So, from our assumption it follows that (r) > 0: Hence, in view of Theorem 2 for each > ; I admits at least one local minimum u such that p pM p < (u) 1 (1 + C1 )jjujjp ; p and our conclusion is achieved. Acknowledgments. The authors would like to thank the anonymous referee for his/her valuable suggestions and comments, which greatly improve the manuscript. References [1] L. Bai and B. Dai, Three solutions for a p-Laplacian boundary value problem with impulsive e¤ects, Appl. Math. Comput., 217(2011), 9895–9904. [2] D. Bainov and P. Simeonov, Systems with Impulse E¤ect, Ellis Horwood Series: Mathematics and Its Applications, Ellis Horwood, Chichester, 1989. [3] M. Benchohra, J. Henderson and S. Ntouyas, Theory of Impulsive Di¤erential Equations, Contemporary Mathematics and Its Applications, 2. Hindawi Publishing Corporation, New York, (2006). [4] G. Bonanno, A critical point theorem via the Ekeland variational principle, Nonlinear Anal., 75 (2012) 2992–3007. [5] G. Bonanno, B. Di Bella and J. Henderson, Existence of solutions to secondorder boundary-value problems with small perturbations of impulses, Electron. J. Di¤erential Equations, 2013(2013), 1–14. [6] G. Bonanno and S. A. Marano, On the structure of the critical set of nondi¤erentiable functions with a weak compactness condition, Appl. Anal., 89(2010), 1–10. [7] G. Bonanno and A. Sciammetta, Existence and multiplicity results to Neumann problems for elliptic equations involving the p-Laplacian, J. Math. Anal. Appl., 390(2012), 59–67. Hssini et al. 31 [8] T. E. Carter, Necessary and su¢ cient conditions for optimal impulsive rendezvous with linear equations of motion, Dyn. Control, 10(2000), 219–227. [9] M. Ferrara, S. Khademloo and S. Heidarkhani, Multiplicity results for perturbed fourth-order Kirchho¤ type elliptic problems, Appl. Math. Comput., 234(2014), 316–325. [10] M. Ferrara and S. Heidarkhani, Multiple solutions for perturbed p-Laplacian boundary-value problems with impulsive e¤ects, Electron. J. Di¤erential Equations, 2014(2014), 1–14. [11] El. M. Hssini, M. Massar and N. Tsouli, Existence and multiplicity of solutions for a p(x)-Kirchho¤ type problems, Bol. Soc. Paran. Mat., 33(2015), 201–215. [12] V. Lakshmikantham, D. D. Bainov and P. S. Simeonov, Theory of Impulsive Di¤erential Equations, Series in Modern Applied Mathematics, vol.6, World Scienti…c, Teaneck, NJ, 1989. [13] X. N. Lin and D. Q. Jiang, Multiple positive solutions of Dirichlet boundary value problems for second order impulsive di¤erential equations, J. Math. Anal. Appl., 321(2006), 501–514. [14] X. Liu and A. R. Willms, Impulsive controllability of linear dynamical systems with applications to maneuvers of spacecraft, Math. Probl. Eng., 2(1996), 277– 299. [15] J. J. Nieto and D. O’Regan, Variational approach to impulsive di¤erential equations, Nonlinear Anal. Real World Appl., 10(2009), 680–690. [16] P. H. Rabinowitz, Minimax Methods in Critical Point Theory with Applications to Di¤erential Equations, CBMS Reg. Conf. Ser. Math., Vol. 65, Amer. Math. Soc., Providence, RI, 1986. [17] B. Ricceri, A general variational principle and some of its applications, J. Comput. Appl. Math., 133(2000), 401–410. [18] B. Ricceri, On a three critical points theorem, Arch. Math., 75(2000), 220–226. [19] Y. Tian and W. Ge, Applications of variational methods to boundary value problem for impulsive di¤erential equations, Proc. Edinburgh Math. Soc., 51(2008), 509–527. [20] Y. Tian and W. Ge, Variational methods to Sturm-Liouville boundary value problem for impulsive di¤erential equations, Nonlinear Anal., 72(2010), 277–287. [21] M. Xiang, B. Zhang and M. Ferrara, Existence of solutions for Kirchho¤ type problem involving the non-local fractional p-Laplacian, J. Math. Anal. Appl., 424(2015), 1021–1041. [22] J. Xu, Z. Wei and Y. Ding, Existence of weak solutions for p-Laplacian problem with impulsive e¤ects, Taiwanese J. Math., 17(2013), 501–515. 32 Existence of Nontrivial Solution for a p-Laplacian Problems [23] D. Zhang and B. Dai, Existence of solutions for nonlinear impulsive di¤erential equations with Dirichlet boundary conditions, Math. Comput. Modelling, 53(2011), 1154–1161.