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Edge isoperimetric number

asked 2020-07-10 22:04:04 +0200

ARG gravatar image

updated 2020-07-11 23:23:00 +0200

This is probably a very silly question. How does one get the edge isoperimetric number of a graph?

As seen under here there should be an algorithm for it, but when I define a graph (say H), then


returns "name 'edge_isoperimetric_number' is not defined"



returns "'Graph' object has no attribute 'edge_isoperimetric_number'"



returns "Object edge_isoperimetric_number not found."

So how do I load said algorithm for use?

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This ticket has not been merged in sage, so that code is not available. You can try to use git to pull the branch on the ticket page, fix the merge conflict and recompile sage after.

FrédéricC gravatar imageFrédéricC ( 2020-07-11 08:16:45 +0200 )edit

Thanks...I've never done that before: what is the merge conflict (or how does one fix such a conflict)?

ARG gravatar imageARG ( 2020-07-11 09:36:23 +0200 )edit

Actually how does one pull this branch? I don't know how to use the commit number 9a0062d887faa15d6e694f7143bd37514f31d790

ARG gravatar imageARG ( 2020-07-11 09:49:02 +0200 )edit

So far... I :

git clone git://

but when I tried to do either

git fetch trac u/vdelecroix/21942


git pull u/vdelecroix/21942


git checkout 7880791d25423e16db76c5f855998818c3c8c45e

or many other numbers in the checkout. But it always returns a error message.

ARG gravatar imageARG ( 2020-07-11 10:21:40 +0200 )edit

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answered 2020-07-11 11:30:22 +0200

FrédéricC gravatar image

There is now a new branch without merge conflict on the trac ticket. So you "just" need to pull and compile. This is quite a task if you are not used to this process.

Some instructions for usage of git for sage developement are here : Please read them carefully.

(1) First, git clone as you did, and then switch to the develop branch.

(2) create a new branch as a copy of "develop" using

git checkout develop  -b some_branch_name_with_cheeger_inside

(3) Then

git pull origin public/ticket/21942

should work and then you will need to compile sage (takes time..)

You may need to configure "trac" as a remote server for git

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Thanks for pointing me in the right direction. At the moment, I get the error:

git_trac.trac_error.TracAuthenticationError: Authentication with trac server failed.

if I try git trac config --user=myusername --pass=mypasswd with my (usual) github usernames and passwords. Then I get the error

fatal: Couldn't find remote ref public/ticket/21942

upon doing git pull origin public/ticket/21942 ...

ARG gravatar imageARG ( 2020-07-11 12:35:48 +0200 )edit

Do not use "git trac". Rather do

git remote add trac -t master
FrédéricC gravatar imageFrédéricC ( 2020-07-11 12:44:19 +0200 )edit

and then

git pull trac public/ticket/21942
FrédéricC gravatar imageFrédéricC ( 2020-07-11 12:44:36 +0200 )edit

git remote add trac -t master printed out fatal: remote trac already exists. But then git pull trac public/ticket/21942 worked, many thanks! I still need to compile ...

ARG gravatar imageARG ( 2020-07-11 13:15:05 +0200 )edit

Compiled and tested, many thanks again. Just a little "bug": the is_connected() function (which the Cheeger functions use) gave an error because it did not like how the vertices of my graph were labeled. After I ran G.relabel() everything went fine.

ARG gravatar imageARG ( 2020-07-11 23:20:39 +0200 )edit

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Asked: 2020-07-10 22:04:04 +0200

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Last updated: Jul 11 '20