Tim; Unfortunately, your query is not like the example you cite because BIND is 
interpreted outside of the basic graph pattern.

Fortunately, in your case you can simply remove the OPTIONAL clause. BIND 
semantics are somewhat similar in that the assigned variable will be unbound if 
the expression fails.

-- Scott

On Nov 30, 2012, at 2:37 PM, Tim Smith <[email protected]> wrote:

> Hi,
> 
> In the following query, why is ?lab not bound inside the OPTIONAL?
> 
> SELECT *
> WHERE {
>       owl:Thing rdfs:label ?lab .
>     OPTIONAL{ 
>     BIND (smf:trim(?lab) as ?lab2).
>     BIND(smf:if(BOUND(?lab), true, false) as ?bound) . } .
> }
> 
> The results of the query using TBC 3.6.1 are:
> 
> ?lab = Thing
> ?lab2 = is unbound
> ?bound = false
> 
> My query is similar to this example from the SPARQL reference page so I'm 
> curious as to why it doesn't work:
> 
> http://www.w3.org/TR/sparql11-query/#optionals
> 
> PREFIX foaf: <http://xmlns.com/foaf/0.1/>
> SELECT ?name ?mbox
> WHERE  { ?x foaf:name  ?name .
>          OPTIONAL { ?x  foaf:mbox  ?mbox }
>        }
> 
> 
> 
> 
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