Filtering statements in a given named-graph

Hi SPARQL gurus

I have a set of statements separated in 2 named graphs :

- some statements appear in named-graph A
- some statements appear in named-graph A and named-graph B

I would like to make a query on statements that are in named-graph A but
_not_ in named-graph B. Is it possible, and how can I do that ?

Thanks
Thomas

Thomas Francart
CTO
Mondeca
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