Mathematical principles | Partial differential equations

Hopf lemma

In mathematics, the Hopf lemma, named after Eberhard Hopf, states that if a continuous real-valued function in a domain in Euclidean space with sufficiently smooth boundary is harmonic in the interior and the value of the function at a point on the boundary is greater than the values at nearby points inside the domain, then the derivative of the function in the direction of the outward pointing normal is strictly positive. The lemma is an important tool in the proof of the maximum principle and in the theory of partial differential equations. The Hopf lemma has been generalized to describe the behavior of the solution to an elliptic problem as it approaches a point on the boundary where its maximum is attained. In the special case of the Laplacian, the Hopf lemma had been discovered by Stanisław Zaremba in 1910. In the more general setting for elliptic equations, it was found independently by Hopf and Olga Oleinik in 1952, although Oleinik's work is not as widely known as Hopf's in Western countries. There are also extensions which allow domains with corners. (Wikipedia).

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In this video I shed some light on a heavily alluded to and poorly explained object, the Hopf Fibration. The Hopf Fibration commonly shows up in discussions surrounding gauge theories and fundamental physics, though its construction is not so mysterious.

From playlist Summer of Math Exposition Youtube Videos

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Hopf Fibration 1

This shows a 3d print of a mathematical sculpture I produced using shapeways.com. This model is available at http://shpws.me/1mUo

From playlist 3D printing

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From playlist Workshop: "Amplitudes and Periods"

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A bagel cut into a Hopf link.

From playlist Algebraic Topology

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Berge's lemma, an animated proof

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From playlist Summer of Math Exposition Youtube Videos

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From playlist 3D printing

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From playlist Quadratic Residues

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From playlist Quantum Groups Seminar

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We present a proof of the Hopf-Rinow theorem. For more details see do Carmo's "Riemannian geometry" Chapter 7.

From playlist Differential geometry

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From playlist Dynamics of Complex Systems - 2017

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From playlist Algebraic Structures in Perturbative Quantum Field Theory: a conference in honour of Dirk Kreimer's 60th birthday

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Inna Entova-Aizenbud: Jacobson-Morozov Lemma for Lie superalgebras using semisimplification

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From playlist Workshop: Monoidal and 2-categories in representation theory and categorification

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Symmetries of hamiltonian actions of reductive groups - David Ben-Zvi

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From playlist Mathematics

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Research lecture at the Worldwide Center of Mathematics.

From playlist Center of Math Research: the Worldwide Lecture Seminar Series

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From playlist Mathematics

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Lukas NABERGALL - Tree-like Equations from the Connes-Kreimer Hopf Algebra...

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From playlist Algebraic Structures in Perturbative Quantum Field Theory: a conference in honour of Dirk Kreimer's 60th birthday

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Burnside's Lemma (Part 2) - combining math, science and music

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From playlist Traditional topics, explained in a new way

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Matt SZCZESNY - Toric Hall Algebras and infinite-dimentional Lie algebras

The process of counting extensions in categories yields an associative (and sometimes Hopf) algebra called a Hall algebra. Applied to the category of Feynman graphs, this process recovers the Connes-Kreimer Hopf algebra. Other examples abound, yielding various combinatorial Hopf algebras.

From playlist Algebraic Structures in Perturbative Quantum Field Theory: a conference in honour of Dirk Kreimer's 60th birthday

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Lionel Roques: Uniqueness of coefficients by strong maximum principle

Find this video and other talks given by worldwide mathematicians on CIRM's Audiovisual Mathematics Library: http://library.cirm-math.fr. And discover all its functionalities: - Chapter markers and keywords to watch the parts of your choice in the video - Videos enriched with abstracts, b

From playlist Partial Differential Equations

Related pages

Mathematics | Stanisław Zaremba (mathematician) | Elliptic operator | Harnack's inequality | Maximum principle | Derivative | Hopf maximum principle | Olga Oleinik | Partial differential equation | Directional derivative | Harmonic function