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7:27 AM
I've suggested adding tag here:
7
Q: Trouble with models of PA and ZFC

PostAsAGuestI have a big trouble in my mind, here is my false reasoning: The Goodstein's theorem is undecidable in (first order) Peano Arithmetic. There exist a non standard model N of PA where the Goodstein's theorem is false. The Goodstein's theorem is provable in ZFC, using ordinals below $\epsilon_...

To me it seems a reasonable tag - the question is about models of Peano Arithmetic.
There is also , but Goodstein theorem seems only tangential to the question, so that one should not be added, right?
BTW the above question got into HNQ list.
 
 
1 hour later…
8:51 AM
Since it is, to some extent, related to usage of the , I thought that it might be useful to have basic information about sandbox(ex) in the tag-info.
I made a suggested edit with some basic information. However, I am mostly familiar with how sandboxes work on math.SE. So if some MO regular checks whether something should be changed/added there, I'll be grateful. (Of course, I am aware that at least two users will see the tag-info in suggested edits review queue, but I thought it is worth mentioning this also here.)
 
 
12 hours later…
9:08 PM
Usage of the lattice-related tags seem to be still a bit unclear.
Aug 4 '15 at 17:25, by quid
@Martin this is an unresolved issue. I think it is best to avoid the tag "lattices" and maybe also "lattice-theory."
18
Q: What "lattices" do we need?

user9072The tag lattices is a problem since a long time. Over the years there were varied discussions about this, but no clear resolution emerged, though some things were done to better the situation. This is an attempt at a fresh start of the discussion to find a long-term solution. The current situa...

I assume we could more-or-less follow tag-excerpt.
The tag-info for lattices says: "Lattices as they are used in number theory. (Not to be confused with lattice theory or lattices as used in physics!)"
The tag-info for lattice-theory says: "The theory of lattices in the sense of order theory. For the number-theoretic notion, use the tag "lattices" instead."
Although the tag-wiki for lattices is not consistent with the above.
 

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