authorGuus Schreiber <guus.schreiber@vu.nl>
Tue, 12 Nov 2013 17:26:03 +0100
changeset 1286 c75100c1162b
parent 1285 717681a2da64
child 1287 5268ce13484c
--- a/rdf-primer/index.html	Tue Nov 12 14:34:55 2013 +0100
+++ b/rdf-primer/index.html	Tue Nov 12 17:26:03 2013 +0100
@@ -507,8 +507,9 @@
-<p class="note">The syntactic is a prefix notation wich will be
-discussed in more detail in Sec. <a href="">"Writing RDF
+<p class="note">The syntactic form (thrid column) is in a prefix
+notation wich will be 
+discussed in more detail in Sec. <a href="#section-graph-syntax">"Writing RDF
 Graphs"</a>. The fact that the constructs have two different prefixes
 (<code>rdf:</code> and <code>rdfs:</code>) is a somewhat annoying
 historical artefact, which is preserved for backward
@@ -525,7 +526,7 @@
   &lt;is a good friend of&gt; &lt;subPropertyOf&gt; &lt;is a friend of&gt;
-<p>One of first RDF Schemas used worldwide is the
+<p>One of first RDF Schemas used worldwide was the
 <a href="http://www.foaf-project.org/">"Friend of a Friend"</a> (FOAF)
 schema for describing social networks. Other examples of RDF
 vocabularies are:</p>
@@ -570,28 +571,33 @@
 <section id="section-graph-syntax">
     <h2>Writing RDF graphs</h2>
-    <p>RDF graphs can be expressed in many syntactic forms.
-    We give an overview of these various syntaxes below, and illustrate
-    them using the example above.</p>
+    <p>Many different concrete syntaxes exist for RDF. In the next two
+    subsections we show RDF syntax examples using the Turtle and Trig
+    language, because these two languages are best suited for human
+    consumption. The final subsection lists the other RDF syntaxes,
+    which include RDFa (for HTML embedding), JSON-LD,
+    N-Triples/N-Quads (line-based exchange formats) and RDF/XML. In
+    Appendix <a href="#section-other-syntaxes">"RDF syntax
+    examples"</a> the reader can find for each RDF syntax
+    corresponding examples of the Turtle/TriG examples in this
+    section. </p>
     <section id="subsection-turtle">
-      <p>Turtle [[TURTLE]] provides a convenient syntax for RDF graphs, introducing numerous
-      syntax shortcuts, such as the
+      <p>Turtle [[TURTLE]] provides a syntax for RDF
+      graphs, which is convenient for humans. Turtle It introduces numerous 
+      syntax shortcuts, such as
       support for namespaces, lists and shorthands for datatyped 
       literals. Turtle provides a good trade-off between ease of
       writing, ease of parsing and readability. Our single-graph example can be
       represented in Turtle as follows.</p>
-      <p>@@ explain example step-by-step</p>
       <pre class="example" id="turtle-example">
 01  @base &lt;http://example.org/&gt; .
 02  @prefix foaf: &lt;http://xmlns.com/foaf/0.1/&gt; .
@@ -615,16 +621,35 @@
 21  &lt;http://data.europeana.eu/item/04802/243FA8618938F4117025F17A8B813C5F9AA4D619&gt;
 22    dcterms:subject wd:Q12418 .
-      </pre>
-    </section>
+<p>Lines 1-6 contain a number of directives which provide shorthands for
+writing down IRIs. A URI like <code>http://xmlns.com/foaf/0.1/</code>
+is colloquially called a namespace URI, in this case of the FOAF
+vocabulary. The "base" prefix is used if no prefix is provided 
+(see <code>bob#me</code>on line 8). A period is used to signal the end
+of a Turtle sentence. </p>
+<p>Lines 8-12 show how Turtle provides a shorthand for a group of
+triples about the same subject. Lines 9-12 specify predicate-object
+part of triples with <code>http://example.org/bob#me</code> as
+subject. The semicolon at the end of lines 9-11 indicate that the
+group is not yet complete. This is the triple represented by line 10 in its expanded form:</p> 
+http://example.org/bob#me http://xmlns.com/foaf/0.1/knows http://example.org/alice#me .
     <section id="subsection-trig">
       <p>TriG [[TRIG]] is an extension to the Turtle syntax enabling
-      the exchange of multiple graphs in the form of RDF datasets. For example we could write 
+      the exchange of multiple graphs in the form of RDF datasets. For
+      example we could write  
       our multi-graph example in TriG as follows.</p>
       <pre class="example" id="trig-example">
@@ -709,7 +734,7 @@
 <section id="section-semantics">
-    <h2>RDF Graphs and what you can do with them</h2>
+    <h2>Semantics of RDF Graphs</h2>
     <p>@@ example: derive that Alice is a person</p>
@@ -730,7 +755,7 @@
   <h2>Document roadmap</h2>  
-<section id="section-syntaxes" class="appendix">
+<section id="section-other-syntaxes" class="appendix">
    <h2>Examples of RDF syntaxes</h2>