user131753
8:55 AM
11:37 AM
Also, you can see that in general mathematicians, even logicians, do not precisely specify what they mean. The use of ellipsis ("...") is never precise, but making the desired notion precise is probably too troublesome and not worth the effort. In this case however, it caused a little confusion because it suggested that n >= 1.
2 hours later…
user131753
1:25 PM
I forgot to delete the last comment. I understand his answer in the sense that what he seems to write is perfectly clear to me. But I don't understand his answer in the sense that I don't see how his answer exactly proves that the "closure of a closed formula" (from the definition given I can't even make sense what the formal representation of it will be) is the formula itself. I think that we need to define it, rather than trying to prove it. What do you think @user21820?
user131753
2:47 PM
user131753
3:32 PM
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