XF2 is a module for use in the Flora-2 (Ergo Lite) logic programming language. It is designed to create a tree-structured explanation for how a grounded query is proven in Flora-2.
It uses a meta-programming approach based on a paper "An explanation shell for expert systems" by Sterling and Lalee. It is created as part of the Singapore Management University Centre for Computational Law's research into domain specific programming languages for legal purposes.
It is written by Jason Morris.
You must have Flora-2 installed on your machine and start the Flora-2
interpreter. Then add the xf2 module to your main module using [+'xf2'].
at the interpreter (assuming you are in the xf2 directory).
If you want to test xf2 with one of the example rulesets provided, you
can load the example ruleset and xf2 with the command ['module',+'xf2'].
Then create an object of type xf2Explanation, and set it's goal attribute to a reified query with no variables.
A reified query is surrounded with ${}.
For example, if using the 'mortal' module provided, and the query is
mortal(Socrates), the code would be e:xf2Explanation[goal->${mortal(Socrates)}]..
If you are using the 'family' module provided, and the query is
Wednesday[sibling->Pugsley], the code would be
e:xf2Explanation[goal->${Wednesday[sibling->Pugsley}]..
Then, you can display the explanation by calling e[display].
In these exapmles e can be replaced with whatever you want.
Provided tests can be run by executing ['xf2tests']. in Flora-2.
- Generate tree-structured explanations for predicate or frame ground queries that use conjunction, disjunction, naf negation, base facts, and boolean truth values.