Removed references to non existing example.

Author: kenwenzel

docs/index.adoc

@@ -77,24 +77,18 @@ uses a native tree structure while RDF is graph-based. For compound
 objects OpenMath-XML can rely on the tree structure to represent syntax
 trees of OpenMath expressions.
 
-As an example Figure #fig:openmath-xml-baum[[fig:openmath-xml-baum]]
-shows on the left side the abstract syntax tree of the expression
-latexmath:[$sin(x + y)$] and on the right side the respective
-OpenMath-XML encoding. For the representation of application objects
-(`OMA`) in RDF the additional property `:arguments` is required. It
+For the representation of application objects (OMA) in RDF the additional property `:arguments` is required. It
 references a list of arguments while the property `:operator` determines
 the function that is applied to to the arguments. A similar
 representation is also used for the other compound objects _binding_
 (OMBIND), _attribution_ (OMATTR) and _error_ (OME). This is in line with
 the OpenMath JSON encoding that also uses additional properties to
 represent parent-child relationships.
 
-The resulting RDF representation of the expression is shown in
-Listing #lst:openmath-rdf[[lst:openmath-rdf]]. Caused by the additional
-properties the syntax is less compact as with the XML format but offers
-stronger semantics. For example, the meaning of the child elements is
-directly expressed through the properties `:operator` and `:arguments`.
+The resulting RDF representation of the expression `sin(x + y)` is shown in following example.
 
+[#lst-openmath-rdf-example]
+.Example: RDF encoding of `sin(x + y)`
 [source,turtle]
 ....
 @prefix : <http://numerateweb.org/vocab/math#> .
@@ -111,6 +105,11 @@ directly expressed through the properties `:operator` and `:arguments`.
   ) .
 ....
 
+Caused by the additional
+properties the syntax is less compact as with the XML format but offers
+stronger semantics. For example, the meaning of the child elements is
+directly expressed through the properties `:operator` and `:arguments`.
+
 === References
 
 References are used within the XML and binary encodings to share