Left downward monotonicity

Left downward monotonicity is a property of a determiner D in Generalized Quantifier Theory. A determiner D is left downward monotone if and only if in a domain of entities E condition (i) holds.

(i) for all A, B, A' subset E: if D(A,B) and A' subset A, then D(A',B)

Left downward monotonicity can be tested as in (ii); as shown there, all and no are left downward monotone, but some and exactly two are not.

(ii) a If all/no animals walked, then all/no dogs walked. b If some/exactly two animals walked, then some/exactly two dogs walked.

Other terms are antipersistent and left monotone decreasing.

Link
Utrecht Lexicon of Linguistics