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Abstract and Applied Analysis
VolumeΒ 2012Β (2012), Article IDΒ 489353, 12 pages
doi:10.1155/2012/489353
Research Article

Monotonic Positive Solutions of Nonlocal Boundary Value Problems for a Second-Order Functional Differential Equation

1Faculty of Science, Alexandria University, Alexandria, Egypt
2Faculty of Science, Garyounis University, Benghazi, Libya

Received 13 October 2011; Accepted 5 December 2011

Academic Editor: IstvánΒ Györi

Copyright Β© 2012 A. M. A. El-Sayed 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.

Abstract

We study the existence of at least one monotonic positive solution for the nonlocal boundary value problem of the second-order functional differential equation π‘₯ ξ…ž ξ…ž ( 𝑑 ) = 𝑓 ( 𝑑 , π‘₯ ( πœ™ ( 𝑑 ) ) ) , 𝑑 ∈ ( 0 , 1 ) , with the nonlocal condition βˆ‘ π‘š π‘˜ = 1 π‘Ž π‘˜ π‘₯ ( 𝜏 π‘˜ ) = π‘₯ 0 , π‘₯ ξ…ž βˆ‘ ( 0 ) + 𝑛 𝑗 = 1 𝑏 𝑗 π‘₯ ξ…ž ( πœ‚ 𝑗 ) = π‘₯ 1 , where 𝜏 π‘˜ ∈ ( π‘Ž , 𝑑 ) βŠ‚ ( 0 , 1 ) , πœ‚ 𝑗 ∈ ( 𝑐 , 𝑒 ) βŠ‚ ( 0 , 1 ) , and π‘₯ 0 , π‘₯ 1 > 0 . As an application the integral and the nonlocal conditions ∫ 𝑑 π‘Ž π‘₯ ( 𝑑 ) 𝑑 𝑑 = π‘₯ 0 , π‘₯ ξ…ž ( 0 ) + π‘₯ ( 𝑒 ) βˆ’ π‘₯ ( 𝑐 ) = π‘₯ 1 will be considered.

1. Introduction

The nonlocal boundary value problems of ordinary differential equations arise in a variety of different areas of applied mathematics and physics.

The study of nonlocal boundary value problems was initiated by Il’in and Moiseev [1, 2]. Since then, the non-local boundary value problems have been studied by several authors. The reader is referred to [322] and references therein.

In most of all these papers, the authors assume that the function 𝑓 ∢ [ 0 , 1 ] Γ— 𝑅 + β†’ 𝑅 + is continuous. They all assume that l i m π‘₯ β†’ ∞ 𝑓 ( π‘₯ ) π‘₯ = 0 o r ∞ , l i m π‘₯ β†’ 0 𝑓 ( π‘₯ ) π‘₯ = 0 o r ∞ . ( 1 . 1 ) These assumptions are restrictive, and there are many functions that do not satisfy these assumptions.

Here we assume that the function 𝑓 ∢ [ 0 , 1 ] Γ— 𝑅 + β†’ 𝑅 + is measurable in 𝑑 ∈ [ 0 , 1 ] for all π‘₯ ∈ 𝑅 + and continuous in π‘₯ ∈ 𝑅 + for almost all 𝑑 ∈ [ 0 , 1 ] is and there exists an integrable function π‘Ž ∈ 𝐿 1 [ 0 , 1 ] and a constant 𝑏 > 0 such that | | | | ≀ | | | | [ ] 𝑓 ( 𝑑 , π‘₯ ) π‘Ž ( 𝑑 ) + 𝑏 | π‘₯ | , βˆ€ ( 𝑑 , π‘₯ ) ∈ 0 , 1 Γ— 𝐷 . ( 1 . 2 ) Our aim here is to study the existence of at least one monotonic positive solution for the nonlocal problem of the second-order functional differential equation π‘₯ ξ…ž ξ…ž ( 𝑑 ) = 𝑓 ( 𝑑 , π‘₯ ( πœ™ ( 𝑑 ) ) ) , 𝑑 ∈ ( 0 , 1 ) , ( 1 . 3 ) with the nonlocal condition π‘š  π‘˜ = 1 π‘Ž π‘˜ π‘₯ ξ€· 𝜏 π‘˜ ξ€Έ = π‘₯ 0 , π‘₯ ξ…ž ( 0 ) + 𝑛  𝑗 = 1 𝑏 𝑗 π‘₯ ξ…ž ξ€· πœ‚ 𝑗 ξ€Έ = π‘₯ 1 , ( 1 . 4 ) where 𝜏 π‘˜ ∈ ( π‘Ž , 𝑑 ) βŠ‚ ( 0 , 1 ) , πœ‚ 𝑗 ∈ ( 𝑐 , 𝑒 ) βŠ‚ ( 0 , 1 ) , a n d π‘₯ 0 , π‘₯ 1 > 0 .

As an application, the problem with the integral and nonlocal conditions ξ€œ 𝑑 π‘Ž π‘₯ ( 𝑑 ) 𝑑 𝑑 = π‘₯ 0 , π‘₯ ξ…ž ( 0 ) + π‘₯ ( 𝑒 ) βˆ’ π‘₯ ( 𝑐 ) = π‘₯ 1 , ( 1 . 5 ) is studied.

It must be noticed that the nonlocal conditions π‘₯ ( 𝜏 ) = π‘₯ 0 , 𝜏 ∈ ( π‘Ž , 𝑑 ) , π‘₯ ξ…ž ( 0 ) + π‘₯ ξ…ž ( πœ‚ ) = π‘₯ 1 , πœ‚ ∈ ( 𝑐 , 𝑒 ) , π‘š  π‘˜ = 1 π‘Ž π‘˜ π‘₯ ξ€· 𝜏 π‘˜ ξ€Έ = 0 , 𝜏 π‘˜ ∈ ( π‘Ž , 𝑑 ) , π‘₯ ξ…ž ( 0 ) + 𝑛  𝑗 = 1 𝑏 𝑗 π‘₯ ξ…ž ξ€· πœ‚ 𝑗 ξ€Έ = 0 , πœ‚ 𝑗 ξ€œ ∈ ( 𝑐 , 𝑒 ) , 𝑑 π‘Ž π‘₯ ( 𝑑 ) 𝑑 𝑑 = 0 , π‘₯ ξ…ž ( 0 ) + π‘₯ ( 𝑒 ) = π‘₯ ( 𝑐 ) ( 1 . 6 ) are special cases of our the nonlocal and integral conditions.

2. Integral Equation Representation

Consider the functional differential equation (1.3) with the nonlocal condition (1.4) with the following assumptions.(i) 𝑓 ∢ [ 0 , 1 ] Γ— 𝑅 + β†’ 𝑅 + is measurable in 𝑑 ∈ [ 0 , 1 ] for all π‘₯ ∈ 𝑅 + and continuous in π‘₯ ∈ 𝑅 + for almost all 𝑑 ∈ [ 0 , 1 ] and there exists an integrable function π‘Ž ∈ 𝐿 1 [ 0 , 1 ] , and a constant 𝑏 > 0 such that | | | | ≀ | | | | [ ] 𝑓 ( 𝑑 , π‘₯ ) π‘Ž ( 𝑑 ) + 𝑏 | π‘₯ | , βˆ€ ( 𝑑 , π‘₯ ) ∈ 0 , 1 Γ— 𝐷 . ( 2 . 1 ) (ii) πœ™ ∢ ( 0 , 1 ) β†’ ( 0 , 1 ) is continuous.(iii) βˆ‘ 𝑏 < 1 / ( 3 βˆ’ 𝐡 ) , 𝐡 = ( 𝑛 𝑗 = 1 𝑏 𝑗 + 1 ) βˆ’ 1 .(iv) π‘š  π‘˜ = 1 π‘Ž π‘˜ > 0 , βˆ€ π‘˜ = 1 , 2 , … , π‘š , 𝑛  𝑗 = 1 𝑏 𝑗 > 0 , βˆ€ 𝑗 = 1 , 2 , … , 𝑛 . ( 2 . 2 ) Now, we have the following Lemma.

Lemma 2.1. The solution of the nonlocal problem (1.3)-(1.4) can be expressed by the integral equation ξƒ― π‘₯ π‘₯ ( 𝑑 ) = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ°  βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 + 𝐡 𝑑 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξƒͺ ξƒ― 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , ( 2 . 3 ) where βˆ‘ 𝐴 = ( π‘š π‘˜ = 1 π‘Ž π‘˜ ) βˆ’ 1 βˆ‘ , 𝐡 = ( 𝑛 𝑗 = 1 𝑏 𝑗 + 1 ) βˆ’ 1 .

Proof. Integrating (1.3), we get π‘₯ ξ…ž ( 𝑑 ) = π‘₯ ξ…ž ( ξ€œ 0 ) + 𝑑 0 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 . ( 2 . 4 ) Integrating (2.4), we obtain π‘₯ ( 𝑑 ) = π‘₯ ( 0 ) + π‘₯ ξ…ž ( ξ€œ 0 ) 𝑑 + 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 . ( 2 . 5 ) Let 𝑑 = 𝜏 π‘˜ , in (2.5), we get π‘š  π‘˜ = 1 π‘Ž π‘˜ π‘₯ ξ€· 𝜏 π‘˜ ξ€Έ = 𝑛  π‘˜ = 1 π‘Ž π‘˜ π‘₯ ( 0 ) + 𝑛  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξ…ž ( 0 ) + π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , ( 2 . 6 ) and we deduce that ξƒ― π‘₯ π‘₯ ( 0 ) = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξ…ž ( 0 ) βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ°  βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , 𝐴 = π‘š  π‘˜ = 1 π‘Ž π‘˜ ξƒͺ βˆ’ 1 . ( 2 . 7 ) Substitute from (2.7) into (2.5), we obtain ξƒ― π‘₯ π‘₯ ( 𝑑 ) = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ° βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 + π‘₯ ξ…ž  ( 0 ) 𝑑 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ ξƒͺ + ξ€œ 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 . ( 2 . 8 ) Let 𝑑 = πœ‚ 𝑗 , in (2.4), we obtain 𝑛  𝑗 = 1 𝑏 𝑗 π‘₯ ξ…ž ξ€· πœ‚ 𝑗 ξ€Έ = 𝑛  𝑗 = 1 𝑏 𝑗 π‘₯ ξ…ž ( 0 ) + 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 π‘₯ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , 1 βˆ’ π‘₯ ξ…ž ( 0 ) = π‘₯ ξ…ž ( 0 ) 𝑛  𝑗 = 1 𝑏 𝑗 + 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , ( 2 . 9 ) and we deduce that π‘₯ ξ…ž  π‘₯ ( 0 ) = 𝐡 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒͺ  𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , 𝐡 = 𝑛  𝑗 = 1 𝑏 𝑗 ξƒͺ + 1 βˆ’ 1 . ( 2 . 1 0 ) Substitute from (2.10) into (2.8), we obtain ξƒ― π‘₯ π‘₯ ( 𝑑 ) = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ°  βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 + 𝐡 𝑑 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξƒͺ ξƒ― 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° , + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , ( 2 . 1 1 ) which proves that the solution of the nonlocal problem (1.3)-(1.4) can be expressed by the integral equation (2.3).

3. Existence of Solution

We study here the existence of at least one monotonic nondecreasing solution π‘₯ ∈ 𝐢 [ 0 , 1 ] for the integral equation (2.3).

Theorem 3.1. Assume that (i)–(iv) are satisfied. Then the nonlocal problem (1.3)-(1.4) has at least one solution π‘₯ ∈ 𝐢 [ 0 , 1 ] .

Proof. Define the subset 𝑄 π‘Ÿ βŠ‚ 𝐢 ( 0 , 1 ) by 𝑄 π‘Ÿ = { π‘₯ ∈ 𝐢 ∢ | π‘₯ ( 𝑑 ) | ≀ π‘Ÿ , π‘Ÿ = ( 𝐴 π‘₯ 0 + 𝐡 π‘₯ 1 + ( 3 βˆ’ 𝐡 ) β€– π‘Ž β€– ) / ( 1 βˆ’ ( 3 βˆ’ 𝐡 ) 𝑏 ) , π‘Ÿ > 0 } . Clear the set 𝑄 π‘Ÿ which is nonempty, closed, and convex.
Let 𝐻 be an operator defined by ξƒ― π‘₯ ( 𝐻 π‘₯ ) ( 𝑑 ) = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ°  βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 s + 𝐡 𝑑 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξƒͺ ξƒ― 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 . ( 3 . 1 )
Let π‘₯ ∈ 𝑄 π‘Ÿ , then | | | | ξƒ― π‘₯ ( 𝐻 π‘₯ ) ( 𝑑 ) ≀ 𝐴 0 + π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ | | | | ξƒ°  βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 + 𝐡 𝑑 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξƒͺ ξƒ― 1 + 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 | | | | ξƒ° + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 0 | | | | ξƒ― π‘₯ ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 ≀ 𝐴 0 + π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 1 0 ξ€Ί | | | | | | | | ξ€» ξƒ° ξƒ― π‘₯ π‘Ž ( 𝑠 ) + 𝑏 π‘₯ ( πœ™ ( 𝑠 ) ) 𝑑 𝑠 + 𝐡 1 + 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ 1 0 ξ€Ί | | | | | | | | ξ€» ξƒ° + ξ€œ π‘Ž ( 𝑠 ) + 𝑏 π‘₯ ( πœ™ ( 𝑠 ) ) 𝑑 𝑠 1 0 ξ€Ί | | π‘Ž | | | | π‘₯ | | ξ€» ( 𝑠 ) + 𝑏 ( πœ™ ( 𝑠 ) ) 𝑑 𝑠 ≀ 𝐴 π‘₯ 0 + β€– π‘Ž β€– + 𝑏 s u p 𝑑 ∈ 𝐼 | | | | π‘₯ ( πœ™ ( 𝑑 ) ) + 𝐡 π‘₯ 1 + 𝐡 𝑛  𝑗 = 1 𝑏 𝑗 β€– π‘Ž β€– + 𝑏 𝐡 𝑛  𝑗 = 1 𝑏 𝑗 s u p 𝑑 ∈ 𝐼 | | | | + π‘₯ ( πœ™ ( 𝑑 ) ) β€– π‘Ž β€– + 𝑏 s u p 𝑑 ∈ 𝐼 | | | | π‘₯ ( πœ™ ( 𝑑 ) ) ≀ 𝐴 π‘₯ 0 + 𝐡 π‘₯ 1 + 2 β€– π‘Ž β€– + 2 𝑏 β€– π‘₯ β€– + ( 1 βˆ’ 𝐡 ) β€– π‘Ž β€– + 𝑏 ( 1 βˆ’ 𝐡 ) β€– π‘₯ β€– ≀ 𝐴 π‘₯ 0 + 𝐡 π‘₯ 1 + ( 3 βˆ’ 𝐡 ) β€– π‘Ž β€– + ( 3 βˆ’ 𝐡 ) 𝑏 π‘Ÿ ≀ π‘Ÿ , ( 3 . 2 ) then 𝐻 ∢ 𝑄 π‘Ÿ β†’ 𝑄 π‘Ÿ and { 𝐻 π‘₯ ( 𝑑 ) } is uniformly bounded in 𝑄 π‘Ÿ .
Also for 𝑑 1 , 𝑑 2 ∈ [ 0 , 1 ] such that 𝑑 1 < 𝑑 2 , we have ξ€· 𝑑 ( 𝐻 π‘₯ ) 2 ξ€Έ ξ€· 𝑑 βˆ’ ( 𝐻 π‘₯ ) 1 ξ€Έ  𝑑 = 𝐡 2 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξƒͺ ξƒ― 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑑 ) ) ) 𝑑 𝑠 𝑑 2 0 ξ€· 𝑑 2 ξ€Έ  𝑑 βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑑 ) ) ) 𝑑 𝑠 βˆ’ 𝐡 1 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξƒͺ ξƒ― 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° βˆ’ ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑑 ) ) ) 𝑑 𝑠 𝑑 1 0 ξ€· 𝑑 1 ξ€Έ ξ€· 𝑑 βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑑 ) ) ) 𝑑 𝑠 = 𝐡 2 βˆ’ 𝑑 1 ξ€Έ ξƒ― π‘₯ 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + ξ€œ 𝑓 ( s , π‘₯ ( πœ™ ( 𝑑 ) ) ) 𝑑 𝑠 𝑑 1 0 ξ€· 𝑑 2 βˆ’ 𝑑 1 ξ€Έ + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑑 ) ) ) 𝑑 𝑠 𝑑 2 𝑑 1 ξ€· 𝑑 2 ξ€Έ βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑑 ) ) ) 𝑑 𝑠 . ( 3 . 3 ) Then | | ξ€· 𝑑 ( 𝐻 π‘₯ ) 2 ξ€Έ ξ€· 𝑑 βˆ’ ( 𝐻 π‘₯ ) 1 ξ€Έ | | | | 𝑑 ≀ 𝐡 2 βˆ’ 𝑑 1 | | ξƒ― π‘₯ 1 + 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξ€Ί | | | | | | | | ξ€» ξƒ° + | | 𝑑 π‘Ž ( 𝑠 ) + 𝑏 π‘₯ ( πœ™ ( 𝑠 ) ) 𝑑 𝑠 2 βˆ’ 𝑑 1 | | ξ€œ 𝑑 1 0 ξ€Ί | | | | | | | | ξ€» + ξ€œ π‘Ž ( 𝑠 ) + 𝑏 π‘₯ ( πœ™ ( 𝑠 ) ) 𝑑 𝑠 𝑑 2 𝑑 1 ξ€· 𝑑 2 | | π‘Ž | | | | π‘₯ | | ξ€» | | 𝑑 βˆ’ 𝑠 ξ€Έ ξ€Ί ( 𝑠 ) + 𝑏 ( πœ™ ( 𝑠 ) ) 𝑑 𝑠 ≀ 𝐡 2 βˆ’ 𝑑 1 | | π‘₯ 1 + 𝑛  𝑗 = 1 𝑏 𝑗 [ ] + | | 𝑑 β€– π‘Ž β€– + 𝑏 π‘Ÿ 2 βˆ’ 𝑑 1 | | [ ] + ξ€œ β€– π‘Ž β€– + 𝑏 π‘Ÿ 𝑑 2 𝑑 1 ξ€Ί 𝑑 β€– π‘Ž β€– 𝑑 𝑠 + 𝑏 π‘Ÿ 2 βˆ’ 𝑑 1 ξ€» . ( 3 . 4 ) The above inequality shows that | | ξ€· 𝑑 ( 𝐻 π‘₯ ) 2 ξ€Έ βˆ’ ξ€· 𝑑 ( 𝐻 π‘₯ ) 1 ξ€Έ | | ⟢ 0 a s 𝑑 2 ⟢ 𝑑 1 . ( 3 . 5 ) Therefore { 𝐻 π‘₯ ( 𝑑 ) } is equicontinuous. By the Arzelà-Ascoli theorem, { 𝐻 π‘₯ ( 𝑑 ) } is relatively compact.
Since all conditions of the Schauder theorem hold, then 𝐻 has a fixed point in 𝑄 π‘Ÿ which proves the existence of at least one solution π‘₯ ∈ 𝐢 [ 0 , 1 ] of the integral equation (2.3), where l i m 𝑑 β†’ 0 + ξƒ― π‘₯ π‘₯ ( 𝑑 ) = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ° βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 βˆ’ 𝐡 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ ξƒ― π‘₯ 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 = π‘₯ ( 0 ) , l i m 𝑑 β†’ 1 βˆ’ ξƒ― π‘₯ π‘₯ ( 𝑑 ) = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ°  βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 + 𝐡 1 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξƒͺ ξƒ― 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 1 0 ( 1 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 = π‘₯ ( 1 ) . ( 3 . 6 ) To complete the proof, we prove that the integral equation (2.3) satisfies nonlocal problem (1.3)-(1.4). Differentiating (2.3), we get π‘₯ ξ…ž ξƒ― π‘₯ ( 𝑑 ) = 𝐡 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 0 π‘₯ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , ( 3 . 7 ) ξ…ž ξ…ž ( 𝑑 ) = 𝑓 ( 𝑑 , π‘₯ ( πœ™ ( 𝑑 ) ) ) . ( 3 . 8 ) Let 𝑑 = 𝜏 π‘˜ in (2.3), we obtain π‘₯ ξ€· 𝜏 π‘˜ ξ€Έ ξƒ― π‘₯ = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ° + ξ€œ βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , ( 3 . 9 ) which proves π‘š  π‘˜ = 1 π‘Ž π‘˜ π‘₯ ξ€· 𝜏 π‘˜ ξ€Έ = π‘₯ 0 . ( 3 . 1 0 ) Also let 𝑑 = πœ‚ 𝑗 in (3.7), we obtain π‘₯ ξ…ž ξ€· πœ‚ 𝑗 ξ€Έ ξƒ― π‘₯ = 𝐡 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 πœ‚ 𝑗 0 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , ( 3 . 1 1 ) then 𝑛  𝑗 = 1 𝑏 𝑗 π‘₯ ξ…ž ξ€· πœ‚ 𝑗 ξ€Έ = 𝐡 𝑛  𝑗 = 1 𝑏 𝑗 ξƒ― π‘₯ 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 . ( 3 . 1 2 ) Let 𝑑 = 0 in (3.7), we obtain π‘₯ ξ…ž ξƒ― π‘₯ ( 0 ) = 𝐡 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° . 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 ( 3 . 1 3 ) Adding (3.12) and (3.13), we obtain π‘₯ ξ…ž ( 0 ) + 𝑛  𝑗 = 1 𝑏 𝑗 π‘₯ ξ…ž ξ€· πœ‚ 𝑗 ξ€Έ = π‘₯ 1 . ( 3 . 1 4 ) This implies that there exists at least one solution π‘₯ ∈ 𝐢 [ 0 , 1 ] of the nonlocal problem (1.3) and (1.4). This completes the proof.

Corollary 3.2. The solution of the problem (1.3)-(1.4) is monotonic nondecreasing.

Proof. Let 𝑑 1 < 𝑑 2 , we deduce from (2.3) that π‘₯ ξ€· 𝑑 1 ξ€Έ ξƒ― π‘₯ = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ°  𝑑 βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 + 𝐡 1 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξƒͺ ξƒ― 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 1 0 ξ€· 𝑑 1 ξ€Έ ξƒ― π‘₯ βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 < 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ°  𝑑 βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 + 𝐡 2 βˆ’ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ 𝜏 π‘˜ π‘₯ ξƒͺ ξƒ― 1 βˆ’ 𝑛  𝑗 = 1 𝑏 𝑗 ξ€œ πœ‚ 𝑗 0 ξƒ° + ξ€œ 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 2 0 ξ€· 𝑑 2 ξ€Έ ξ€· 𝑑 βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 = π‘₯ 2 ξ€Έ , ( 3 . 1 5 ) which proves that the solution π‘₯ of the problem (1.3)-(1.4) is monotonic nondecreasing.

3.1. Positive Solution

Let 𝑏 𝑗 = 0 , 𝑗 = 1 , 2 , … 𝑛 and π‘₯ 1 = 0 , then the nonlocal problem condition (1.4) will be π‘š  π‘˜ = 1 π‘Ž π‘˜ π‘₯ ξ€· 𝜏 π‘˜ ξ€Έ = π‘₯ 0 , π‘₯ ξ…ž ( 0 ) = 0 . ( 3 . 1 6 )

Theorem 3.3. Let the assumptions (i)–(iv) of Theorem 3.1 be satisfied. Then the solution of the nonlocal problem (1.3)–(3.16) is positive 𝑑 ∈ [ 𝑑 , 1 ] .

Proof. Let 𝑏 𝑗 = 0 , 𝑗 = 1 , 2 , … 𝑛 and π‘₯ 1 = 0 in the integral equation (2.3) and the nonlocal condition (1.4), then the solution of the nonlocal problem (1.3)–(3.16) will be given by the integral equation ξƒ― π‘₯ π‘₯ ( 𝑑 ) = 𝐴 0 βˆ’ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξƒ° + ξ€œ βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , ( 3 . 1 7 ) where βˆ‘ 𝐴 = ( π‘š π‘˜ = 1 π‘Ž π‘˜ ) βˆ’ 1 .
Let 𝑑 ∈ [ 𝑑 , 1 ] , then ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ ξ€œ βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 ≀ 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , 𝜏 π‘˜ ≀ 𝑑 , π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 ≀ π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 . ( 3 . 1 8 ) Multiplying by βˆ‘ 𝐴 = ( π‘š π‘˜ = 1 π‘Ž π‘˜ ) βˆ’ 1 , we obtain 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝜏 π‘˜ 0 ξ€· 𝜏 π‘˜ ξ€Έ βˆ’ 𝑠 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 ≀ 𝐴 π‘š  π‘˜ = 1 π‘Ž π‘˜ ξ€œ 𝑑 0 = ξ€œ ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 , ( 3 . 1 9 ) and the solution π‘₯ of the nonlocal problem (1.3) and (3.16), given by the integral equation (3.17), is positive for 𝑑 ∈ [ 𝑑 , 1 ] . This complete the proof.

Example 3.4. Consider the nonlocal problem of the second-order functional differential equation (1.3) with two-point boundary condition π‘₯ ξ…ž ( 0 ) = 0 , π‘₯ ( πœ‚ ) = π‘₯ 0 , πœ‚ ∈ ( π‘Ž , 𝑑 ) βŠ‚ ( 0 , 1 ) . ( 3 . 2 0 ) Applying our results here, we deduce that the two-point boundary value problem (1.3)–(3.20) has at least one monotonic nondecreasing solution π‘₯ ∈ 𝐢 [ 0 , 1 ] represented by the integral equation π‘₯ ( 𝑑 ) = π‘₯ 0 βˆ’ ξ€œ πœ‚ 0 ( ξ€œ πœ‚ βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 + 𝑑 0 ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 . ( 3 . 2 1 ) This the solution is positive with 𝑑 > πœ‚ .

4. Nonlocal Integral Condition

Let π‘₯ ∈ 𝐢 [ 0 , 1 ] be the solution of the nonlocal problem (1.3) and (1.4).

Let π‘Ž π‘˜ = 𝑑 π‘˜ βˆ’ 𝑑 π‘˜ βˆ’ 1 , 𝜏 π‘˜ ∈ ( 𝑑 π‘˜ βˆ’ 1 , 𝑑 π‘˜ ) βŠ‚ ( π‘Ž , 𝑑 ) βŠ‚ ( 0 , 1 ) and let 𝑏 𝑗 = πœ‰ 𝑗 βˆ’ πœ‰ 𝑗 βˆ’ 1 , πœ‚ 𝑗 ∈ ( πœ‰ 𝑗 βˆ’ 1 , πœ‰ 𝑗 ) βŠ‚ ( 𝑐 , 𝑒 ) βŠ‚ ( 0 , 1 ) , then π‘š  π‘˜ = 1 ξ€· 𝑑 π‘˜ βˆ’ 𝑑 π‘˜ βˆ’ 1 ξ€Έ π‘₯ ξ€· 𝜏 π‘˜ ξ€Έ = π‘₯ 0 , π‘₯ ξ…ž ( 0 ) + 𝑛  𝑗 = 1 ξ€· πœ‰ 𝑗 βˆ’ πœ‰ 𝑗 βˆ’ 1 ξ€Έ π‘₯ ξ…ž ξ€· πœ‚ 𝑗 ξ€Έ = π‘₯ 1 . ( 4 . 1 ) From the continuity of the solution π‘₯ of the nonlocal problem (1.3) and (1.4), we obtain l i m π‘š π‘š β†’ ∞  π‘˜ = 1 ξ€· 𝑑 π‘˜ βˆ’ 𝑑 π‘˜ βˆ’ 1 ξ€Έ π‘₯ ξ€· 𝜏 π‘˜ ξ€Έ = ξ€œ 𝑑 π‘Ž π‘₯ π‘₯ ( 𝑠 ) 𝑑 𝑠 , ξ…ž ( 0 ) + l i m 𝑛 𝑛 β†’ ∞  𝑗 = 1 ξ€· πœ‰ 𝑗 βˆ’ πœ‰ 𝑗 βˆ’ 1 ξ€Έ π‘₯ ξ…ž ξ€· πœ‚ 𝑗 ξ€Έ = π‘₯ ξ…ž ξ€œ ( 0 ) + 𝑒 𝑐 π‘₯ ξ…ž ( 𝑠 ) 𝑑 𝑠 , ( 4 . 2 ) and the nonlocal condition (1.4) transformed to the integral condition ξ€œ 𝑑 π‘Ž π‘₯ ( 𝑠 ) 𝑑 𝑠 = π‘₯ 0 , π‘₯ ξ…ž ( 0 ) + π‘₯ ( 𝑒 ) βˆ’ π‘₯ ( 𝑐 ) = π‘₯ 1 , ( 4 . 3 ) and the solution of the integral equation (2.3) will be π‘₯ ( 𝑑 ) = ( 𝑑 βˆ’ π‘Ž ) βˆ’ 1 ξ‚» π‘₯ 0 βˆ’ ξ€œ 𝑑 π‘Ž ξ€œ 𝑑 0 ξ‚Ό + ( 𝑑 βˆ’ 𝑠 ) 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 𝑑 ( ( 𝑏 βˆ’ 𝑐 ) + 1 ) βˆ’ 1 ξ‚» π‘₯ ( 𝑑 βˆ’ 1 ) 1 βˆ’ ξ€œ 𝑒 𝑐 ξ€œ 𝑑 0 𝑓 ξ‚Ό + ξ€œ ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 𝑑 𝑑 𝑑 0 𝑓 ( 𝑠 , π‘₯ ( πœ™ ( 𝑠 ) ) ) 𝑑 𝑠 . ( 4 . 4 ) Now, we have the following theorem.

Theorem 4.1. Let the assumptions (i)–(iv) of Theorem 3.1 be satisfied. Then the nonlocal problem π‘₯ ξ…ž ξ…ž , ξ€œ ( 𝑑 ) = 𝑓 ( 𝑑 , π‘₯ ( πœ™ ( 𝑑 ) ) ) , 𝑑 ∈ ( 0 , 1 ) 𝑑 π‘Ž π‘₯ ( 𝑠 ) 𝑑 𝑠 = π‘₯ 0 , π‘₯ ξ…ž ( 0 ) + π‘₯ ( 𝑒 ) βˆ’ π‘₯ ( 𝑐 ) = π‘₯ 1 ( 4 . 5 ) has at least one monotonic nondecreasing solution π‘₯ ∈ 𝐢 [ 0 , 1 ] represented by (4.4).

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