Topology

Entourages of a composition of funcoids ★★

Author(s): Porton

Conjecture   $ \forall H \in \operatorname{up} (g \circ f) \exists F \in \operatorname{up} f, G \in \operatorname{up} g : H \sqsupseteq G \circ F $ for every composable funcoids $ f $ and $ g $.

Keywords: composition of funcoids; funcoids

Posted by porton
updated July 12th, 2016
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Graph Theory » Extremal G.T.

Weak saturation of the cube in the clique ★

Author(s): Morrison; Noel

Problem  

Determine $ \text{wsat}(K_n,Q_3) $.

Keywords: bootstrap percolation; hypercube; Weak saturation

Posted by Jon Noel
updated April 6th, 2016
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Geometry

Convex Equipartitions with Extreme Perimeter ★★

Author(s): Nandakumar

To divide a given 2D convex region C into a specified number n of convex pieces all of equal area (perimeters could be different) such that the total perimeter of pieces is (1) maximized (2) minimized.

Remark: It appears maximizing the total perimeter is the easier problem.

Keywords: convex equipartition

Posted by Nandakumar
updated October 22nd, 2015
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Combinatorics

Turán Problem for $10$-Cycles in the Hypercube ★★

Author(s): Erdos

Problem   Bound the extremal number of $ C_{10} $ in the hypercube.

Keywords: cycles; extremal combinatorics; hypercube

Posted by Jon Noel
updated September 20th, 2015
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