Frege's Puzzle and Naive Theory

Nathan Salmon in Frege's Puzzle on the distinction between intension and extension:

"The intension of a singular term, sentence, or predicate is a function that assigns to any possible world w the extension the singular term, sentence, or predicates takes on with respect to w. The extension of a singular term (with respect to a possible world w) is simply its referent (with respect to w), i.e., the object or individual to which the term refers (with respect to w). The extension of a sentence (with resp3ect to w) is its truth value (with respect to w)--either truth or falsehood. The extension of an n-place predicate (with respect to w) is the predicate's semantic characteristic function (with respect to w), i.e., the function that assigns either truth or falsehood to an n-tuple of individuals, according as the predicate or its negation applies (with respect to w) to the n-tuple. Assuming bivalence, the extension of an n-place predicate may be identified instead with the class or n-tuples to which the predicate applies." p.14

Frege's Puzzle--Introduction

Some definitions:

Purely general proposition: a composite purely intensional entity made up solely of further intensional entities such as attributes and concepts, employing purely conceptual representations of the individuals whom the proposition is about in place of the individuals and times themselves. (Fregean view of content)