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The results of this exceptional thesis on free boundary problems in singularly perturbed PDEs develop our understanding of the effects of strong competition between species. The research has a wealth of valuable applications in both physics and biology.

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This thesis is devoted to the study of the asymptotic behavior of singularly perturbed partial differential equations and some related free boundary problems arising from these two problems. We study the free boundary problems in the singulary limit and give some characterizations, and use this to study the dynamical behavior of competing species when the competition is strong. These results have many applications in physics and biology.

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Foreword.- Acknowledgements.- Introduction.- Uniqueness, Stability and Uniform Lipschitz Estimates.- Uniqueness in the Singular Limit.- The Dynamics of One Dimensional Singular Limiting Problem.- Approximate Clean Up Lemma.- Asymptotics in Strong Competition.- The Limited Equation of a Singular Perturbed System.- Reference.- Index._

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