This is one of the things that we discussed in the PRR (Production Rules Representation) that has been postponed until the second version of the specification definition. It was not put in the first one because very few people in OMG understand anything about full opportunistic backward chaining. However, any old ND guy who ever had to program in ND Nexpert / Expert can certainly fill your ear with all of the hows and whys of the system.

Unfortunately, most of them know very little about how the engine operates nor why it does what it does. Ed Virgin and Irwin Welker may be the last two people on Earth who really, really got down into the innards of the engine itself; Ed from a teaching approach and Irwin from the engineering approach. Both are with Fair Isaac - STILL - and I’ll see if I can get more input from them on this.

The other three people who will know the workings (but not the internals) are are also with Fair Isaac (the old ND team of consultants) and I’ll see what I can wring out of them as well - that would be Willie Hall, Don Tallo and myself. At the next PRR meeting we will be discussing event-driven rules as well as the various methods of backward chaining.

SDG
jco

The problem with omitting backward chaining is that deduction becomes impractical. Without an ability to subgoal automatically, forward chaining deduction must be controlled manually in order to avoid infering an “infinity of irrelevant truths”. Thus, most BRE are dumb from a logical standpoint.

W3C will not go the same route. The emphasis on logic there requires much more control over reasoning and problem solving than reactive business rules.

BTW, in general, goals define states intentionally rather than constituting states themselves.

P.S., anyone interested can read an ancient (1985?) paper about backward chaining using the Rete Algorithm. (I’ll upload it and post a blog with a link ASAP.)