[rules-users] rule implementation

Hello, I have 1 Object of Type "A" with a position (x,y) and n Objects of type "B" with postions (x,y) respectively. I want to write a rule which gets 1 Object type "A" and more than 10 Objects of Type "B" as input facts. The rule should determine 10 of the Objects of type "B" which are nearest to the Object of type "B". I would appreciate any help! Regards Thomas