I'm working on an application in Java, that needs to do some complex logic rule deductions as part of its functionality. I'd like to code my logic deductions in Prolog or some other logic/constraint programming language, instead of Java, as I believe the resulting code will be significantly simpler and more maintainable.

I Googled for embedded Java implementations on Prolog, and found number of them, each with very little documentation. My (modest) selection criteria are:

• should be embeddable in Java (e.g. can be bundled up with my java package instead of requiring any native installations on external programs)
• simple interface to use from Java (for initiating deductions, inspecting results, and adding rules)
• come with at least a few examples on how to use it
• doesn't necessarely have to be Prolog, but other logic/constraint programming languages with the above criteria would suit my needs, too.

What choices do I have and what are their advantages and disadvantages?