Ability to attain goals depends on building up associations, simple or complex, between particular changes in states and particular actions that will bring these changes about.
While this strategy may be appropriate for machine learning and problem solving, it is not always suggested for humans (e.g. cognitive load theory and its implications).
This latter case, of which the canonical example is STRIPS, an automated planning computer program, allows task-independent correlation of differences to the operators which reduce them.
Prodigy, a problem solver developed in a larger learning-assisted automated planning project started at Carnegie Mellon University by Jaime Carbonell, Steven Minton and Craig Knoblock, is another system that used MEA.
Professor Morten Lind, at Technical University of Denmark has developed a tool called Multilevel Flow Modeling (MFM).