PREFIX sx: a sx:ShapeDecl ; sx:shapeExpr [ a sx:Shape; sx:expression [ a sx:TripleConstraint; sx:predicate ; sx:valueExpr ] ] . a sx:ShapeDecl ; sx:shapeExpr [ a sx:Shape; sx:expression [ a sx:TripleConstraint; sx:predicate ; sx:valueExpr [ a sx:NodeConstraint; sx:values () ] ] ] . [] a sx:Schema; sx:shapes ( ) .