557 citations
- Goddard Space Flight CenterUS13 papers
- Argonne National LaboratoryUS12 papers
- Columbia UniversityUS12 papers
- Center for Astrophysics Harvard & SmithsonianUS11 papers
- Northwestern UniversityUS10 papers
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- Space Telescope Science InstituteUS9 papers
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Showing 2018 · math.COShow all
3 papers · 2 filters
math.CO2018
Description of closure operators in convex geometries of segments on a line
Kira Adaricheva, Gent Gjonbalaj
Convex geometry is a closure space with the anti-exchange property. A classical result of Edelman and Jamison (1985) claims that every finite convex geometry is a join of s…
math.CO2018★ 2 cited
The Hadwiger-Nelson problem with two forbidden distances
Geoffrey Exoo, Dan Ismailescu
In 1950 Edward Nelson asked the following simple-sounding question: \emph{How many colors are needed to color the Euclidean plane such that no two points distance $1…
math.CO2018★ 1 cited
The chromatic number of the plane is at least 5 - a new proof
Geoffrey Exoo, Dan Ismailescu
We present an alternate proof of the fact that given any 4-coloring of the plane there exist two points unit distance apart which are identically colored.