43 LR One Question 7
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I don't understand how you formed the first part of the conditional. ~M + ~R --> D. I saw the conditional cues but was thrown off by the wording. (I still got the right answer but want to get better at easily representing structure so I can easily see the answer)
Good god. I'm answering this question six months later.* I'm sure jelbey12 has moved on, but maybe someone else will find this useful.
We'll do the whole thing below, but it's one of those cases where it's probably more helpful to think about the relationship than to draw it. Here, the first sentence tells us that if you do Not Rotate, and you do Not take preventive Measures, then you'll Deplete the crop. That's how I formulated it.
Here's the full version. Start from "unless":
1. ~R → D
M
2. → ~R → D
→ M
3. ~M → ~R → D
~R + ~D → M
[note: the negation of a whole conditional is to have the sufficient condition and the negation of the necessary condition at the same time. This makes sense if you think about it: If someone's trying to prove that Not Rotating guarantees your soil will be Depleted, the way to prove them wrong would be to show them some land that had been Not Rotated and was at the same time Not Depleted. Got it? Good. Remember, I told you this was the long way]
From the above:
~R + ~D → M
~M → R or D
So if you do Not take preventive Measures, you must Rotate or you will Deplete the soil: one of those two things must happen. So if you do Not take preventive Measures and you do Not Rotate, you absolutely have to have Depleted soil (and if you ~M and ~D, then it must be that you did R).
Thus,
~M + ~R → D
Ta-dah!
*This scares me; if I didn't get the notification about this comment, how many other comments have I missed? On the other hand, I'm here now because of the comment below that I did get notified about, so maybe instead what happened is I did get a notification for this comment, but accidentally deleted it. Yeah, the more I think about it, the more likely that seems. I guess I'm not scared. But jelbey12, if you ever read this, I'm sorry.
How second sentence can be interpreted into D -> F?
I thought it is D + ~F -> ~C.
(C is crop)
They're the same! If your soil is Depleted and you have No Fertilizer, then you will have No Crop. So if your soil is Depleted, you must have Fertilizer (to have a crop).