pop_icon Wrote:Question states:
T won’t be selected only if G is selected. it must be true that...
- G → T
OR
G → - T
Arcade says it must be true that - G → T
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Only if G is selected would T not be selected. Therefore, if G then no T (G → - T)
How can it be true that if no G is selected that T has to be selected?
You correctly switched the order to "Only if G is selected would T not be selected." However, you're wrong in translating that as "Therefore, if G then no T (G → - T)."
Think about this similar statement:
Only if my son sleeps through the night will I be refreshed in the morning.Does that mean that him sleeping through the night definitely leads to me being refreshed? No. I could be awoken by something else. (Yes, this is me venting about my current lack of sleep!)
But, if I did wake refreshed, it must be true that he slept through the night.
The "only if" almost always indicates the necessary part of the condition.
That clear it up?