Abstract
An elementary proof of the no-retraction theorem in the plane is given by means of the complex square root.
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Acknowledgments
This work was partially supported by projects 20020190100039BA UBACyT and PIP 11220130100006CO CONICET. The author thanks Prof. Rafael Ortega and Prof. Mónica Clapp for their comments on a first version of this manuscript. Also, the author thanks the anonymous reviewers and the editors for the careful reading of the manuscript and fruitful suggestions.
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Notes on contributors
Pablo Amster
Departamento de Matemática - Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires & IMAS-CONICET – Ciudad Universitaria Pab. I – 1428 Buenos Aires, Argentina [email protected]