`CVXPYBackend`: Implement method `remove_constraint`

[mkoeppe]

This method is not implemented, which is blocking us from using CVXPY + CyLP as our new interface to CBC.

• Deprecate sage_numerical_backends_coin in favor of cvxpy+cylp, upgrade cbc to 2.10.10 #35368

[takshakmudgal]

i would like to work on this issue, can you please provide me more info regarding it?

[Eren-Yeaager]

I would like to contribute to this issue. Please assign me

[mkoeppe]

When you try out the branch of #35368 and run the test suite, you will see failures because remove_constraint is missing. You can use these tests to guide your work

[takshakmudgal]

After working on this issue for a while this is what I have figured out. It seems like there is an issue with the implementation of the remove_constraint method in the CVXPYBackend library. Can you provide more information on what this method is supposed to do and why it is necessary for the integration of CVXPY and CyLP as a new interface to CBC? Additionally, it would be helpful to know more about the current approach being taken to solve this issue and if there are any potential workarounds in the meantime.
From what I understand, the CVXPYBackend library is a backend for the CVXPY optimization tool that allows users to solve convex optimization problems using a variety of solvers. The remove_constraint method is used to remove a constraint from the optimization problem, but it is currently not implemented in the library. This is causing issues for users who are trying to integrate CVXPY and CyLP as a new interface to CBC, and it is preventing them from upgrading CBC to version 2.10.8.

[mkoeppe]

there is an issue with the implementation of the remove_constraint method in the CVXPYBackend library.

That's right. The issue is that it is not implemented.

[mkoeppe]

Can you provide more information on what this method is supposed to do

The method is documented in the ABC GenericBackend.

[takshakmudgal]

I have attempted to solve the missing remove_constraint method issue in the CVXPYBackend library by adding the following implementation:

def remove_constraint(self, i):
    del self.constraints[i]

I believe this method should remove the constraint with the specified index i. Could you please let me know if this is the correct approach to solving the issue?

Furthermore, I would like to know how I can perform tests on this implementation. You mentioned earlier that the test suite provided in branch #35368 can be used to guide my work. Could you please provide more information on how to run these tests and how to verify that my implementation is working correctly?

[mkoeppe]

I would like to know how I can perform tests on this implementation.

https://doc.sagemath.org/html/en/developer/doctesting.html

https://doc.sagemath.org/html/en/developer/coding_basics.html#documentation-strings

[takshakmudgal]

I think I have fixed the issue, can you please check and merge my PR.