nonlinear problems for systems of differential equations
TRANSCRIPT
h’onlineor Analysis. 7’heory, Methods & Appkotionr. Vol 4, No 6. p. 1213
0 Pergamon Press Ltd. 1980 Printed in Great Britain
0362.546X/SO’llOl-1213 $02 00/O
ADDENDUM AND CORRIGENDUM
NONLINEAR PROBLEMS FOR SYSTEMS OF DIFFERENTIAL EQUATIONS*
GIUSEPPE ANICHINI
Istituto Matematico ‘U. Dini’, V. le Morgagni 67/A, 50134 Firenze, Italy
Received 21 November 1979
Key words and phrases: Boundary value problems, differential equations, nonlinear operators, fixed point theorems.
THEOREM 3.1 is true and the method of proof is correctly based upon showing the existence of a fixed point of the multivalued transformation U, provided that the following hypothesis is assumed :
(iv)’ There exists a linear operator AU: Y + Ker DU which is continuous with respect to U, for all u E X, such that (2.6) holds.
It is easy to see that, since the nonlinearity of the original boundary operator T is shifted on the operator H, this additional property does not destroy the goodness of the results.
Finally, when ,!,ff has a linear continuous right inverse and, in particular when LE has the in- verse, this hypothesis is trivially satisfied, which is how it is seen almost always in the applications.
* This journal, Vol. 1, No. 6, p. 691 (1977).
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