Homework for Philosophy 270, Fall 2012

Homework on §1.4—assigned Fri 8/31 and due Mon 9/3

(to PDF format)

Define entailment in terms of truth values and possible worlds for the special cases of one and two premises—that is, complete each of the following:

φ ⊨ ψ if and only if ...
φ, ψ ⊨ χ if and only if ...

Give the definitions in both positive and negative form (so complete the patterns above each twice).