Natural Logic

Table of contents


Marks quantifier scope and token polarity, according to natural logic semantics. This is useful for many shallow logical reasoning tasks; most notably the Open IE annotator. The annotator places an OperatorAnnotation on tokens which are quantifiers (or other natural logic operators), and a PolarityAnnotation on all tokens in the sentence.

For example, for the sentence “all cats have tails”, the annotator would mark all as a quantifier with subject scope [1, 2) and object scope [2, 4). In addition, it would mark cats as a downward-polarity token, and all other tokens as upwards polarity.

Property nameAnnotator class nameGenerated Annotation
natlogNaturalLogicAnnotatorOperatorAnnotation, PolarityAnnotation


  • natlog.dopolarity: True by default. If set to false, the annotator will only annotate quantifiers and quantifier scopes, and not annotate the polarity of each token.