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Pairs of positive periodic solutions of nonlinear ODEs with indefinite weight: a topological degree approach for the super–sublinear case

Published online by Cambridge University Press:  16 May 2016

Alberto Boscaggin
Dipartimento di Matematica ‘Giuseppe Peano’, Università di Torino, via Carlo Alberto 10, 10123 Torino, Italy (
Guglielmo Feltrin
SISSA – International School for Advanced Studies, via Carlo Alberto 10, via Bonomea 265, 34136 Trieste, Italy (
Fabio Zanolin
Dipartimento di Matematica, Informatica e Fisica, Università di Udine, via delle Scienze 206, 33100 Udine, Italy(


We study the periodic and Neumann boundary-value problems associated with the second-order nonlinear differential equation

where is a sublinear function at infinity having superlinear growth at zero. We prove the existence of two positive solutions when

and λ > 0 is sufficiently large. Our approach is based on Mawhin's coincidence degree theory and index computations.

Research Article
Copyright © Royal Society of Edinburgh 2016 

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