To the main point: I'm against technological solutions for issues of this type. Perhaps the FAQ on voting down should say something about this possibility as I guess it just might not have occurred to people that it can happen - it's not easy to see how major an edit was and most seem to be simply retagging so it's a fair bet that an answer is an answer to the current form of the question. In general, the community system will sort this out: if you notice an answer you gave has garnered a vote down then go and check it and see if someone has said something like "Doesn't answer the question.". Then edit your answer to make it clear that this was for an earlier form of the question.
Perhaps also we should be better at voting for questions because of how they are asked, not just their content. So if a question is edited in a good way, vote for it and say "+1 for gracious edit" (or whatever).
Always better to praise good behaviour than stamp down on dubious behaviour.
]]>Perhaps vigilant people with edit privileges should step in to re-edit if it is thought that this situation has occurred.
Absolutely agree. If somebody breaks a sensible convention, the best way is to just show the person what the convention is.
Also, sometimes people essentially start a new question/answer thread in the comments to a correct answer. In that case, I tell the asker that he/she's likely to get more by asking a new question.
]]>Clarify meaning without changing it.
Adding new conditions which excludes a counter-example does change the meaning.
Perhaps vigilant people with edit privileges should step in to re-edit if it is thought that this situation has occurred.
]]>Good edits:
Fix grammatical or spelling errors.
Clarify meaning without changing it.
Correct minor mistakes.
Add related resources or links.
Always respect the original author.
Could we add a line to address this issue? Maybe something like "Clearly indicate any edits that change the meaning of the question."?
]]>I do think editing a discussion to clean up unenlightening errors is important to making MathOverflow readable "for posterity". However, ever since Dave Brown suggested it, I discourage completely erasing "enlightening errors", i.e. mistakes I or others have made that other would probably learn something from.
As well, if people make comments as to how a question/answer could be improved, if it's valid, I think the best thing to do for future readers is to just implement the suggestion and reverse-engineer the content, and <i>include accreditation</i> to the people whose comments helps with the improvement. This has the effect of making some comments obsolete, which I think is not unfortunate, as long credit goes to those who deserve it.
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