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,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.
Gramsood dialect you’ll demand after that constraints into the particular good type of variety of identity or algorithm. Such as, variables otherwise aggregate terminology is almost certainly not greeting in a number of metropolitan areas.
Semantic structure. That it design represent the very thought of a beneficial semantic framework (known as translation on literature [Enderton01, Mendelson97]). Semantic structures are acclimatized to understand formulas also to describe analytical entailment. Like with the fresh syntax, this construction has lots of systems you to definitely RIF reasoning languages can specialise to complement their requirements. Such mechanisms are:
For every RIF dialect which is produced by RIF-FLD is explained within the individual document
- Number of specifics values. RIF-FLD is made to complement languages that support reason with contradictory and you can unclear guidance. Every logics that are designed to manage such items try multi-respected. For that reason, RIF-FLD postulates that there surely is a couple of basic facts thinking, Tv, that has the values t (true) and you can f (false) and maybe others. Instance, the brand new RIF Earliest Logic Dialect [RIF-BLD] is one or two-cherished, but most other languages might have a lot more insights thinking.
- Semantic structures. Semantic structures regulate how the many signs on the alphabet of a good dialect are translated and just how basic facts viewpoints was 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 framework. It framework defines the overall values for mapping the new demonstration sentence structure away from RIF-FLD towards tangible XML interchange format. For example:
For each and every RIF dialect that is based on RIF-FLD was described in individual file
- A specification of one’s XML syntax to possess RIF-FLD, for instance the associated XML Schema document.
- A requirements from a one-to-that mapping about speech syntax away from RIF-FLD so you’re able to the XML syntax. That it mapping need chart one better-molded algorithm out of RIF-FLD so you can an enthusiastic XML particularly file that’s appropriate in accordance to your aforementioned XML Schema document.
It specs ‘s the most recent draft of one’s RIF-FLD meaning. vanilla umbrella giriÅŸ The initial particularly dialect, the latest RIF First Logic Dialect, try discussed from inside the [RIF-BLD]. A center dialect, that is defined because of the next focusing RIF-BLD, are specified in the [RIF-Core].
