add document on semantics options and add options to terminology docu…

…ment

docs/rdf-terminology.md

@@ -134,3 +134,11 @@
 * [Valid](https://w3c.github.io/rdf-semantics/spec/#dfn-valid) – Any process which constructs a graph E from some other graph S is (simply) valid if S [simply entails](https://w3c.github.io/rdf-semantics/spec/#dfn-simply-entail) E in every case, otherwise invalid.
 * [Value space](https://w3c.github.io/rdf-semantics/spec/#dfn-value-space) – The value space of a datatype is the range of the [lexical-to-value mapping](https://w3c.github.io/rdf-concepts/spec/#dfn-lexical-to-value-mapping).
 * [Vocabulary](https://w3c.github.io/rdf-semantics/spec/#dfn-vocabulary) – A vocabulary is a set of [names](https://w3c.github.io/rdf-semantics/spec/#dfn-name).
+
+## New terms:
+
+* [Opaque semantics] – Any semantics for quoted triples where the syntactic form of the arguments to triples is important.  See [docs/semantics.md] for more information.
+
+* [Semi-opaque (semi-transparent semantics] – Any semantics for quoted triples where the syntactic form of the arguments to triples is important, except that only the meaning of blank nodes is important.  See [docs/semantics.md] for more information.
+
+* [Transparent semantics] – Any semantics for quoted triples where only the meaning of the arguments to triples is important.  See [docs/semantics.md] for more information.

docs/semantics.md

@@ -0,0 +1,87 @@
+# RDF-star Semantics Options
+
+There have been several different semantics proposals for quoted triples, some with multiple semantics.  The proposed semantics differ in technical details but also differ in the entailments they support.  The major differences between semantics can be summarized in whether they are sensitive to the precise syntax of quoted triples or only to the semantics of the components of quoted triples.   The first kind of semantics have been called opaque and the second kind transparent.  There is also a semi-opaque (or semi-transparent) semantics, as in the community report, where the syntax of IRIs and literals are important but only the meaning of blank nodes is.
+
+The difference between the semantics can be seen in the following examples.
+
+In RDF (extended to include owl:sameAs as equality to provide a way of requiring that two different IRIs mean the same thing)
+```
+:b owl:sameAs :c .
+_:a :b "4"^^xsd:int .
+```
+entails
+```
+_:f :b "4"^^xsd:int .
+```
+and 
+```
+_:a :b "4"^^xsd:integer .
+```
+and 
+```
+_:a :c "4"^^xsd:integer .
+```
+
+
+## Transparent Semantics
+
+In the transparent semantics
+```
+:b owl:sameAs :c .
+<<_:a :b "4"^^xsd:int >> :d :e .
+```
+entails
+```
+<<_:f :b "4"^^xsd:int >> :d :e .
+```
+and 
+```
+<<_:a :b "4"^^xsd:integer >> :d :e .
+```
+and
+```
+<<_:a :c "4"^^xsd:int >> :d :e .
+```
+
+## Opaque Semantics
+
+In the opaque semantics
+```
+:b owl:sameAs :c .
+<<_:a :b "4"^^xsd:int >> :d :e .
+```
+does not entail
+```
+<<_:f :b "4"^^xsd:int >> :d :e .
+```
+or 
+```
+<<_:a :b "4"^^xsd:integer >> :d :e .
+```
+or
+```
+<<_:a :c "4"^^xsd:int >> :d :e .
+```
+
+## Semi-opaque (Semi-transparent) Semantics
+
+In the semi-opaque (semi-transparent) semantics
+```
+:b owl:sameAs :c .
+<<_:a :b "4"^^xsd:int >> :d :e .
+```
+does entail
+```
+<<_:f :b "4"^^xsd:int >> :d :e .
+```
+but does not entail
+```
+<<_:a :b "4"^^xsd:integer >> :d :e .
+```
+or
+```
+<<_:a :c "4"^^xsd:int >> :d :e .
+```
+
+One could also create other semi-opaque semantics where either IRIs or literals were transparent.
+