@prefix log: <http://www.w3.org/2000/10/swap/log#> .


{ 
  (
   {:a :b :c} 
   { 
     {?x :b :c} 
     => 
     {:m :n ?x} 
   } 
  ) 
  log:filter 
  ?z 
} 
=> 
{?z a :Thing} .