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mattbaker.blog | ||
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awwalker.com
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| | | | | Classification theorems of Euler, Lagrange, and Legendre describe the sets of integers that can be written as the sum of 2, 3, and 4 squares. In the last two cases, it follows easily that the density of these sets are 5/6 and 1. The question of density is not so simple in the case of... | |
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fabricebaudoin.blog
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| | | | | In this lecture, we studySobolev inequalities on Dirichlet spaces. The approach we develop is related to Hardy-Littlewood-Sobolev theory The link between the Hardy-Littlewood-Sobolev theory and heat kernel upper bounds is due to Varopoulos, but the proof I give below I learnt it from my colleague RodrigoBañuelos. It bypasses the Marcinkiewicz interpolation theorem,that was originally used... | |
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algorithmsoup.wordpress.com
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| | | | | The ``probabilistic method'' is the art of applying probabilistic thinking to non-probabilistic problems. Applications of the probabilistic method often feel like magic. Here is my favorite example: Theorem (Erdös, 1965). Call a set $latex {X}&fg=000000$ sum-free if for all $latex {a, b \in X}&fg=000000$, we have $latex {a + b \not\in X}&fg=000000$. For any finite... | |
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xorshammer.com
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| | | Here's a puzzle: You and Bob are going to play a game which has the following steps. Bob thinks of some function $latex f\colon \mathbb{R}\to\mathbb{R}$ (it's arbitrary: it doesn't have to be continuous or anything). You pick an $latex x \in \mathbb{R}$. Bob reveals to you the table of values $latex \{(x_0, f(x_0))\mid x_0\ne x\}$... | ||