For-instance, the fresh new trademark from the a symbol
p might allow p to appear in a term of the form f(p), but disallow it to occur in a term like p(a beneficial,b). The signature for f, on the other hand, might allow that symbol to appear in f(p) and f(p,q), but disallow f(p,q,r) and f(f). In this way, it is possible to control which symbols are used for predicates and which adam4adam for functions, where variables can occur, and so on.
A dialect you will impose subsequent limits on the kind of an effective particular brand of term otherwise algorithm. Eg, details or aggregate terms may not be greet in a number of places.
Semantic construction. That it construction represent the notion of a great semantic framework (known as translation on the books [Enderton01, Mendelson97]). Semantic formations are acclimatized to understand algorithms also to establish analytical entailment. Like with the fresh new syntax, this build has a great amount of components you to RIF reason languages can also be specialise to fit their requirements. Such elements tend to be:
Each RIF dialect that is produced by RIF-FLD would-be revealed within the own document
- Gang of specifics opinions. RIF-FLD is designed to complement dialects one to support cause which have inconsistent and you will not sure recommendations. All the logics that are designed to handle these types of things was multi-respected. Consequently, RIF-FLD postulates there is a collection of facts opinions, Tv, which has the costs t (true) and you may f (false) and maybe someone else. Such as, the RIF Very first Reason Dialect [RIF-BLD] was two-appreciated, but other dialects might have additional truth values.
- Semantic formations. Semantic formations determine how the many symbols from the alphabet of an excellent dialect is interpreted and how details thinking is allotted to formulas.
- Datatypes. Some symbol spaces that are part of the RIF syntactic framework have fixed interpretations. For instance, symbols in the symbol space are always interpreted as sequences of Unicode characters, and a ? b for any pair of distinct symbols. A symbol space whose symbols have a fixed interpretation in any semantic structure is called a datatype.
- Entailment. This notion is fundamental to logic-based dialects. Given a set of formulas (e.g., facts and rules) G, entailment determines which other formulas necessarily follow from G. Entailment is the main mechanism underlying query answering in Databases, Logic Programming, and the various reasoning tasks in Description Logics.
A set of formulas G logically entails another formula g if for every semantic structure I in some set S, if G is true in I then g is also true in I. Almost all logics define entailment this way. The difference lies in which set S they use. For instance, logics that are based on the classical first-order predicate calculus, such as most Description Logics, assume that S is the set of all semantic structures. In contrast, most Logic Programming languages use default negation. Accordingly, the set S contains only the so-called minimal Herbrand models [Lloyd87] of G and, furthermore, only the minimal models of a special kind. See [Shoham87] for a more detailed exposition of this subject.
XML serialization structure. Which design represent all round standards to own mapping the fresh presentation sentence structure off RIF-FLD to the concrete XML interchange format. This includes:
For each and every RIF dialect that is produced by RIF-FLD is revealed within its own document
- A requirements of XML syntax having RIF-FLD, like the relevant XML Outline document.
- A specification away from a single-to-one to mapping on demonstration sentence structure from RIF-FLD to the XML sentence structure. Which mapping must chart any well-shaped algorithm regarding RIF-FLD to help you an enthusiastic XML instance document that’s appropriate in accordance toward aforementioned XML Schema file.
It specs ‘s the newest draft of your own RIF-FLD definition. The initial like dialect, brand new RIF First Reasoning Dialect, is demonstrated for the [RIF-BLD]. A key dialect, that’s defined from the after that focusing RIF-BLD, is actually specified within the [RIF-Core].