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Semantic formations are often discussed regarding a specific place away from datatypes, denoted of the DTS

Semantic formations are often discussed regarding a specific place away from datatypes, denoted of the DTS

A semantic structure, I, is a tuple of the form
  • an associated set, called the really worth space, and you may
  • a mapping from the lexical area of your own symbol space so you’re able to the significance room, titled lexical-to-value-area mapping. ?

During the a concrete dialect, DTS always has the fresh datatypes supported by you to definitely dialect. Every RIF dialects need to support the https://datingranking.net/afrointroductions-review datatypes that will be listinged in Part Datatypes regarding [RIF-DTB]. Their well worth spaces additionally the lexical-to-value-place mappings for those datatypes try discussed in the same point.

Although the lexical and the value spaces might sometimes look similar, one should not confuse them. Lexical spaces define the syntax of the constant symbols in the RIF language. Value spaces define the meaning of the constants. The lexical and the value spaces are often not even isomorphic. For example, 1.2^^xs:quantitative and 1.20^^xs:quantitative are two legal — and distinct — constants in RIF because 1.2 and step one.20 belong to the lexical space of xs:quantitative. However, these two constants are interpreted by the same element of the value space of the xs:quantitative type. Therefore, step one.2^^xs:decimal = step 1.20^^xs:quantitative is a RIF tautology. Likewise, RIF semantics for datatypes implies certain inequalities. For instance, abc^^xs:sequence ? abcd^^xs:string is a tautology, since the lexical-to-value-space mapping of the xs:string type maps these two constants into distinct elements in the value space of xs:sequence.

3.cuatro Semantic Formations

The fresh main step-in specifying a model-theoretical semantics having a reasoning-centered words was determining the notion of an effective semantic structure. Semantic formations are widely used to designate basic facts viewpoints to help you RIF-FLD algorithms.

Definition (Semantic structure). C, IV, IF, INF, Ilist, Itail, Iframe, Isub, Iisa, I=, Iexternal, Iconnective, Itruth>. Here D is a non-empty set of elements called the domain of I. We will continue to use Const to refer to the set of all constant symbols and Var to refer to the set of all variable symbols. TV denotes the set of truth values that the semantic structure uses and DTS is a set of identifiers for datatypes.

A semantic structure, I, is a tuple of the form
  • Each pair <s,v> ? ArgNames ? D represents an argument/value pair instead of just a value in the case of a positional term.
  • The brand new argument in order to an expression that have named objections is actually a small purse of argument/worthy of sets as opposed to a small ordered series of effortless issues.
  • Bags are used here because the order of the argument/value pairs in a term with named arguments is immaterial and the pairs may repeat: p(a->b good->b). (However, p(a->b a->b) is not equivalent to p(a->b), as we shall see later.)

To see why such repetition can occur, note that argument names may repeat: p(a->b a->c). This can be understood as treating a as a bag-valued argument. Identical argument/value pairs can then arise as a result of a substitution. For instance, p(a->?A a beneficial->?B) becomes p(a->b an effective->b) if the variables ?Good and ?B are both instantiated with the symbol b.

A semantic structure, I, is a tuple of the form
  • Ilist : D * > D
  • Itail : D + ?D > D

A semantic structure, I, is a tuple of the form
  • The function Ilist is injective (one-to-one).
  • The set Ilist(D * ), henceforth denoted Dlist , is disjoint from the value spaces of all data types in DTS.
  • Itail(a1, . ak, Ilist(ak+step 1, . ak+yards)) = Ilist(a1, . ak, ak+step one, . ak+m).

Note that the last condition above restricts Itail only when its last argument is in Dlist. If the last argument of Itail is not in Dlist, then the list is a general open one and there are no restrictions on the value of Itail except that it must be in D.

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