There was a download of Prolog.NET Workbench 1.0 on the developer's website when we last checked. We cannot confirm if there is a free download of this software available.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The most popular version of the tool is 1.0. The default filename for the program's installer is Prolog.Workbench.exe. The software is categorized as Development Tools. The actual developer of the free software is Richard G. Todd.
From the developer:
Prolog.NET Workbench is a .NET-base implementation of Prolog based on the Warren Abstract Machine (WAM) architecture.
This project contains:
* Prolog - the primary assembly containing the Prolog.NET compiler and interpreter.
* PrologLibrary - an assembly containing external functions callable by Prolog.NET programs.
* PrologSchedule - a WPF application demonstrating the use of Prolog.NET from a client C# application.
You may want to check out more software, such as Visual Prolog, SWI-Prolog or Spices.Net Obfuscator Evaluation, which might be similar to Prolog.NET Workbench.