5 July 2025

Finally, Java Geometry Expert (JGEX) is available via web access, without the requirement of installing it for the native platform you have. It is supported by the CheerpJ technology.

Here is a short demo what one can do right now with this tool. When starting the online version, CheerpJ must be downloaded by the user's browser (this is done automatically by the webpage, so do not worry, everything will just work out-of-the-box). This may require time, but surely much less time than installing the program natively. (In many schools, in fact, you cannot install anything in the computer lab, even if you are a teacher. Only the system administrator can do that, but you may be unlucky if he is away on his 2-month holidays. Even if he is around, there will be perhaps no way to install anything without further permissions of the school authorities, and if still possible, it may surely require much time, weeks or months, etc. You probably know what I am talking about!)

Let us try the menu Help > About JGEX first. It recalls the original authors: Shang Ching Chou, Xiao Shan Gao and Zheng Ye, pioneers of automated deduction in geometry: well-known experts of the topic. One can see that Java 11 (an internal version, provided by CheerpJ) is running in the background, compiled into WebAssembly by the CheerpJ developers, and running through a content delivery network (CDN).

Now, by opening Examples > 1_TOP_TEN > 08_9point, one may want to click on the green icon that symbolizes a PLAY button. It computes a proof with the selected method (by default, the Geometry Deductive Database method, GDD).

Recent versions of JGEX automatically show the GDD proof tree in a different window. In the web version, however, all opened windows are displayed inside the tab of the JGEX application. The resolution of the output may be somewhat low, and current version of JGEX still do not support further analysis of the proof in that window. But there is a new option File > Open GDD Proof in GraphViz Online:

GraphViz Online's GV-visualizer allows the user to study the proof steps more detailed. Not only the explanatory texts are displayed when hovering the vertices of the proof graph, but by clicking on them, the user gets a graphical explanation as well:

Now, some activity for you: try to change the language of the web application by choosing Options > Preferences > Mode > Language. Click Save Preferences, then OK, OK, and reload the webpage. Hopefully, you can use JGEX in the selected language without any difficulties now! Anyway, please let us know on GitHub Issues if your mother tongue is not yet among the supported versions.

Credits. The big work for this new version was done by Philip Hallwirth, my bachelor student at PHDL. Thanks, Phil!