This file is from Wikimedia Commons and may be used by other projects.
The description on its file description page there is shown below.
Summary
DescriptionTSP cutting plane.png
Illustrates the intersection of the unit cube with the cutting plane . In the context of the Traveling salesman problem on three nodes, this (rather weak) inequality states that every tour must have at least two edges.
This diagram image could be re-created using vector graphics as an SVG file. This has several advantages; see Commons:Media for cleanup for more information. If an SVG form of this image is available, please upload it and afterwards replace this template with {{vector version available|new image name}}.
It is recommended to name the SVG file “TSP cutting plane.svg”—then the template Vector version available (or Vva) does not need the new image name parameter.
Licensing
I, the copyright holder of this work, hereby publish it under the following licence:
to share – to copy, distribute and transmit the work
to remix – to adapt the work
Under the following conditions:
attribution – You must give appropriate credit, provide a link to the licence, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible licence as the original.