Abstract
While so far automated knowledge base construction has largely focused on fully qualified facts, e.g., , the Web contains also extensive amounts of existential information in the form of cardinality assertions, e.g., that someone has two children without giving their names. In this paper we argue that the extraction of such information could substantially increase the scope of knowledge bases. For the sample of the hasChild relation in Wikidata, we show that simple regular-expression based extraction from Wikipedia can increase the size of the relation by 178%. We also show how such cardinality information can be used to estimate the recall of knowledge bases.