On Monday, we’ll work on Chapter 2, sections 4 and 5. Exam #1 is one week from today. It covers Chapters 1 and 2 (except for chapter 2, section 6). On Monday, I’ll give you a more detailed outline.

‘→’ is the arrow; it abbreviates “if...then...” and equivalent constructions If I win the lottery, then I’ll be rich. (W: Rob wins the lottery; R: Rob will be rich) use only one arrow; put the “if” condition (the antecedent) on the left, the “then” condition (the consequent) on the right: write W → R not → W → R

When ‘if’ appears alone (not ‘only if’ or ‘if and only if’) the statement(s) following it should be the antecedent (the left side) of your conditional. The same rule applies to ‘provided that’. Tammy will come to the party, if she’s invited. (P: Tammy will come to the party; I: Tammy is invited to the party) I → P

If she’s invited, Tammy will come to the party. I → P Tammy will come to the party only if she’s invited. (This is taken to mean that she won’t come if she’s not invited.) P → I

Also, sufficient condition = antecedent, necessary condition = consequent If you’re a human, then you’re a mammal. (H: You’re a human; M: You’re a mammal) Sufficient → necessary H → M but if someone says that being a mammal is sufficient for being a human, then write M → H, even though the statement is false.

‘↔’ is the double-arrow; it abbreviates ‘if and only if’ and equivalent phrases (such as ‘just in case’) Martha is brilliant if and only if she is a genius. (B: Martha is brilliant; G: Martha is a genius) B ↔ G

Exercises, pp