log:imply meaning. => symbol in N3

The question is about notation 3 interpretation.

For the statement S : { ?A :a ?B } => { ?B :x :y }

it is a logical expression as:   exists triple "?A :a ?B" => exists triple "?B :x :y"

or it is a dedcution rule as: if  exists triple "?A :a ?B" then create triple "?B :x :y"

Best regards
Luc