The truth is in here
First four solvers help you solving recommendation or classification problems, i.e. mapping several input attributes/criteria/parameters into output attribute/goal/recommendation/diagnosis.
One can split complex problem into several simpler subproblems and solve them by most suitable tool. Now orchestration is performed by Prolog with the special functor fire. Knowlus is in permanent development. So more and more intelligent tools will be introduced in near future. The most anticipated tool is a decision support.
More info in presentation.