-
Notifications
You must be signed in to change notification settings - Fork 90
New issue
Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.
By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.
Already on GitHub? Sign in to your account
Replaced |- ( [ x / y ]
with |- ( [ y / x ]
in set.mm, iset.mm and nf.mm
#3571
Merged
Merged
Changes from all commits
Commits
Show all changes
3 commits
Select commit
Hold shift + click to select a range
File filter
Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
There are no files selected for viewing
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Oops, something went wrong.
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Why does this proof become so much longer?
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Because I made the cosmetic choice of keeping
x = y
in the hypothesis instead of switching intoy = x
. Do you prefer to havey = x
, but with the original proof length? (For me it's fine both ways).Some useful data might be that currently
x = y
appears 486 times in iset.mm, whiley = x
appears only 19 times (and most of those 19 times are there to show commutation properties).There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
@GinoGiotto thank you for the explanation. We should not switch the antecedent in the hypothesis (
x = y
should be the preferred way), so we can keep the longer proof.There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I don't really have an opinion about these renamings, as long as they are only renamings.
When we write
x = y -> ( ph <-> ps )
, this generally goes with DV(x,ps) and/or DV(y,ph), so if you swap x and y, do it consistently. (I haven't checked the present case.)There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I didn't know that x is coupled with ps and y is coupled with ph. I'll try to fix this in a next PR.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
I do not know what @benjub wants to say with his comment, and I don't see any need for a fix/change: DV(x,ps) means that x does not occur in ps, but of course y can (and usually should) occur in ps, analogously with ph. So we (usually) have ps(y) and ph(x). If the theorem is valid without DV conditions, they should not be added.
There was a problem hiding this comment.
Choose a reason for hiding this comment
The reason will be displayed to describe this comment to others. Learn more.
Of course, DV conditions should not be added if they are not necessary. What I mean is that when they are needed, it is usual to write that kind of hypotheses as
x = y -> (ph(x) <-> ps(y))
(or sometimesx = y -> (ph(x,y) <-> ps(y))
orx = y -> (ph(x) <-> ps(x,y))
), where I made explicit the variables that may occur instead of the variables that do not.