SHEBS@UTAH-20.ARPA (01/12/84)
From: Stanley T. Shebs <SHEBS@UTAH-20.ARPA>
I'm looking for info on a formal taxonomy of production rule systems,
sufficiently precise that it can distinguish OPS5 from YAPS, but also say
that they're more similar than either of them is to Prolog. The only
relevant material I've seen is the paper by Davis & King in MI 8, which
characterizes PSs in terms of syntax, complexity of LHS and RHS, control
structure, and "programmability" (seems to mean meta-rules). This is
a start, but too vague to be implemented. A formal taxonomy should
indicate where "holes" exist, that is, strange designs that nobody has
built. Also, how would Georgeff's (Stanford STAN-CS-79-716) notion of
"controlled production systems" fit in? He showed that CPSs are more
general than PSs, but then one can also show that any CPS can be represented
by some ordinary PS. I'm particularly interested in formalization of
the different control strategies - are text order selection (as in Prolog)
and conflict resolution (as in OPS5) mutually exclusive, or can they be
intermixed (perhaps using text order to find 5 potential rules, then
conflict resolution to choose among the 5). Presumably a sufficiently
precise taxonomy could answer these sorts of questions. Has anyone
looked at these questions?
stan shebs