CDEG: Computerized Diagrammatic Euclidean Geometry

This is the home page for CDEG: Computerized Diagrammatic Euclidean Geometry, which impliments a formal system for giving diagrammatic proofs in planar geometry that are similar to the kinds of proofs Euclid gives in the Elements. Currently, CDEG exists in two versions: 2.0 beta (text-driven menu interface), and 3.0 alpha (Graphical User Interface), both of which can be downloaded from this web page.  CDEG is under active development, so CDEG 3.0 is likely to change frequently.

CDEG 2.0 requires X11 to be already installed in order to run on Mac OS or Unix/linux systems.  X11 for mac can be downloaded and installed from the Xquartz project.  CDEG 3.0 does not require X11.  All versions of CDEG are distributed as zipped files which must be extracted to use.  The program files are not signed, so you will most likely need to tell your computer to let them run anyway.  In many cases you can do this by right-clicking on the application.

CDEG is free software, released under the terms of the Gnu Public License, version 3, as published by the Free Software Foundation.

You can download CDEG 2.0, which is run through a text-driven menu, in the following forms:

Or, you can download the most recent version, CDEG 3.0 alpha, which is run through a graphical user interface that is easier to use for most people.  This version is still under active development, so it doesn't include any documentation beyond what is found in the program itself, and likely still contains bugs, but, unlike version 2, it doesn't require X11 and is also available in a Windows version:

Please let me know if you are using this program, and especially if you find any bugs! If you find bugs please send a transcript of the session in which the bug occurred to me at  Thanks for trying it out!

My other publications relating to CDEG can be downloaded from my research page.

Nathaniel Miller <>