Function Rule
http://www.ksl.stanford.edu/software/IW/registry/SRC/IW-TEAM.daml
Fri Jan 17 17:59:36 PST 2003
Wed Feb 05 13:26:54 PST 2003
This proof step is used when the goal has been proved through some form of procedural attachment.
The goal (+ 3 2) would be solved by an arithmetic module, and the proof returned would be a FunctionProofStep.