For-instance, the fresh signature of a symbol

For-instance, the fresh signature of 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(good,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 for functions, where variables can occur, and so on.

An effective dialect you’ll impose then limitations with the variety of an excellent version of type of label otherwise formula. Particularly, details otherwise aggregate conditions may possibly not be invited in some towns and cities.

Semantic framework. This construction describes the notion of an effective semantic framework (labeled as translation throughout the literary works [Enderton01, Mendelson97]). Semantic structures are widely used to interpret algorithms and also to identify logical entailment As with this new sentence structure, it design has a great amount of mechanisms one to RIF reason languages normally specialise to match their requirements. This type of components tend to be:

For each RIF dialect that’s produced from RIF-FLD might be demonstrated within its own file

  • Gang of information philosophy. RIF-FLD is made to complement languages one support reasoning which have contradictory and you can not sure recommendations. All of the logics that will handle this type of points is actually multi-respected. Thus, RIF-FLD postulates that there’s some knowledge values, Television, which has the costs t (true) and you may f (false) and perhaps anybody else. Like, new RIF Earliest Reasoning Dialect [RIF-BLD] is a couple-valued, however, almost every other languages might have additional truth beliefs.
  • Semantic formations. Semantic structures regulate how different symbols regarding the alphabet from good dialect is actually translated and how insights viewpoints was assigned to algorithms.
  • 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 construction. Which structure talks of the general values having mapping the new presentation syntax away from RIF-FLD for the tangible XML interchange format. This includes:

For every RIF dialect that’s produced from RIF-FLD would be discussed within the very own document

  • A specification of the XML syntax to own RIF-FLD, for instance the associated XML Schema file.
  • A specification out of a-one-to-you to mapping on presentation syntax of RIF-FLD to its XML syntax. That it mapping need to map one well-shaped formula out-of RIF-FLD so you’re able to a keen XML such as for example document which is valid in accordance for the aforementioned XML Outline document.

This specs ’s the newest draft of your RIF-FLD definition. The original including dialect, the brand new RIF Very first Logic Dialect, are discussed for the [RIF-BLD]. A key dialect, that’s laid out from the after that concentrating RIF-BLD, try given inside the [RIF-Core].