Month: March 2017

Note: copied from the output of a computer program. === adjacency matrix: 0 0 0 0 0 1 1 1 0 0 0 0 1 0 0 0 0 1 0 1 1 0 0 0 0 0 0 0 1 0 0 1 0 0 0 0 0 1 0 0 1 0 0… Continue reading Data on possible/probable 15-vertex, 37-edge unit distance graph

With respect to the readline library, some versions have various symbols (UP, etc.) defined, and some do not. For PARI/gp on my system, it only works when these various symbols are defined.   PARI/gp question: how does one get a history of the commands input at the terminal ?     We are in the… Continue reading Using the ldd command with the verbose option

The post from a few weeks ago shows a 14-vertex 33-edge probable unit distance graph with 324 4-colorings. The URL of that blog post = “Best candidate” graph, 14 vertices, udg

It’s a probable unit distance graph. It has 356 4-colorings, and is not 3-colorable. Its adjacency matrix is: 0 0 0 0 0 0 0 0 1 0 0 1 1 0 0 0 0 0 1 0 1 1 1 0 0 1 0 0 0 1 0 1 0 0 1 0 1… Continue reading Figure of a 13-vertex 28-edge graph

I had read that EXIF metadata in files that are images, whether .jpg or other file formats, have embbedded data, sometimes inluding geotags (coordinates). Below is the copy/paste of my first test running exiftool.exe on Windows 10: C:\Users\abcde\Downloads> C:\Users\abcde\Downloads\exiftool -All Louvre_Museum_Wikimedia_Commons.jpg ExifTool Version Number : 10.45 File Name : Louvre_Museum_Wikimedia_Commons.jpg Directory : . File Size… Continue reading My first test-drive using exiftool on Windows

The 12-vertex, 26-edge graph shown above is not 3-colorable, and is 4-colorable in 178 ways, up to permutation of the four colors. Numerical evidence suggests that it is a unit distance graph, i.e. embeddable in the plane with all edges of unit length. My unit distance graph solver found no 12-vertex, non 3-colorable, 4-colorable udg… Continue reading A 12-vertex, 26-edge, probable unit distance graph