Logical Forms
1. **State the problem:**
We analyze the logical forms of the statements using the variables:
- $W$: It is Wednesday
- $S$: I will go shopping
- $M$: I will go to a movie
2. **Write the statements in logical form:**
(a) If it is Wednesday, then I will go shopping and I will not go to a movie:
$$W \to (S \wedge \neg M)$$
(b) I will go shopping only if it is Wednesday and I will not go to a movie:
"Only if" means implication from $S$ to $W \wedge \neg M$:
$$S \to (W \wedge \neg M)$$
(c) {I will go shopping and not go to a movie} is a sufficient condition for it to be Wednesday:
Sufficient condition means:
$$(S \wedge \neg M) \to W$$
(d) {I will go shopping and not go to a movie} is a necessary condition for it to be Wednesday:
Necessary condition means:
$$W \to (S \wedge \neg M)$$
3. **Compare statements (b)-(d) to (a) and its converse:**
- Statement (a) is:
$$W \to (S \wedge \neg M)$$
- The converse of (a) is:
$$(S \wedge \neg M) \to W$$
4. **Check equivalences:**
- (b) is $$S \to (W \wedge \neg M)$$ which is not equivalent to (a) or its converse.
- (c) is $$(S \wedge \neg M) \to W$$ which is the converse of (a).
- (d) is $$W \to (S \wedge \neg M)$$ which is exactly (a).
5. **Summary:**
- (b) is not equivalent to (a) or its converse.
- (c) is equivalent to the converse of (a).
- (d) is equivalent to (a).
Thus, the logical equivalences are clearly identified.