Formal Logic 1.3

A symbol that looks like an upside down A, read as "for all," "for every," "for each," or "for any."

A symbol that looks like a backward E, read as "there exists one," "for at least one," or "for some."

wffs containing predicates and quantifiers.

"Grouping symbols" such as parentheses and brackets that identify the section of the well-formed formula (wff) to which the quantifier applies.

A variable that occurs somewhere is a well-formed formula (wff) where it is not part of a quantifier and is not within the scope of a quantifier involving that variable.

Such as for a well-formed formula (wff) it it is True in all possible interpretations.