Actually, I pasted the wrong query in. It should look something like:
CONSTRUCT {?this Relex:ratio ?ratio}
WHERE
{
{ SELECT (sum(?rate) AS ?sysRate)
WHERE {?this a Relex:Failure .
?this Relex:refsSystem ?system .
?system Relex:failsAs
Sub-queries (like LET and aggregations) are native ARQ extensions that
have not reached standard status yet. It is likely that they will be
added to SPARQL 1.1, but currently the SPIN syntax does not support
them. I will add this to our TODO list, but cannot promise any date
for this
