Electron. J. Differential Equations, Vol. 2024 (2024), No. 55, pp. 1-13.

Existence and bounds for Kneser-type solutions to noncanonical third-order neutral differential equations

Ganesh Purushothaman, Kannan Suresh, Ethiraju Thandapani, Ercan Tunc

Abstract:
This article focuses on the existence and asymptotic behavior of Kneser-type solutions to third-order noncanonical differential equations with a delay or advanced argument in the neutral term $$ \Big(r_2(t)\big(r_1(t)z'(t)\big)'\Big)'+g(t)x(t)=0, $$ where \(z(t)=x(t)+p(t)x(\tau(t))\). This equation is transformed into a canonical equation, which reduces the number of classes of positive solutions from 4 to 2. This is done without assuming extra conditions, and greatly simplifies the process of obtaining conditions for the existence of Kneser-type solutions. Also we obtain lower and upper bounds for these solutions, and obtain their rate of convergence to zero. Two examples are provided to illustrate our main results, one with a delay neutral term, and one with an advanced neutral term.

Submitted July 25, 2024. Published September 19, 2024.
Math Subject Classifications: 34C10, 34K11, 34K40.
Key Words: Kneser solution; neutral differential equation; noncanonical equation.
DOI: 10.58997/ejde.2024.55

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Ganesh Purushothaman
Department of Mathematics
St. Joseph's College of Engineering
Chennai - 600119, India
email: gpmanphd@gmail.com
Kannan Suresh
Department of Mathematics
St. Joseph's College of Engineering
Chennai - 600119, India
email: dhivasuresh@gmail.com
Ethiraju Thandapani
Ramanujan Institute for Advanced Study in Mathematics
University of Madras, Chennai - 600005, India
email: ethandapani@yahoo.co.in
Ercan Tunç
Department of Mathematics, Faculty of Arts and Sciences
Tokat Gaziosmanpasa University, 60240, Tokat, Turkiye
email: ercantunc72@yahoo.com

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