Quantifier

A quantifier is a logical operator which bounds a variable. Every quantifier must apply to some variable. Some examples of quantifiers include $\forall ,\exists ,\exists ^{\infty },\exists !,\exists ^{=n},Q,\star ,\Box ,\Diamond ,$ and $\Delta ^{\sharp }$. These roughly correspond to natural language quantifiers such as "all", "some", "exists finitely many", "probably exists".