Macaulay2 / Macaulay2/M2

bug in Module / Module

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Core
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Macaulay2
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Description

I believe this should be an error:
```m2
i1 : R = kk[x];

i2 : M = module ideal x^2;

i3 : N = comodule ideal x^2;

i4 : M / N

o4 = cokernel | 1 |

1
o4 : R-module, quotient of R
```
N is not a submodule of M, and they're not submodules of the same module either for `(M+N)/N` to make sense. The output doesn't even make sense as vector spaces, since M is the span of {x^2, x^3, ...} and N is the span of {1, x}.

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Research direction

Reproduce the displayed Macaulay2 commands involving M = module ideal x^2, N = comodule ideal x^2, and M / N. The issue provides no file or test path; done means the invalid quotient is rejected with an error because N is not a submodule of M or of the same ambient module.

Written by the indexing model from the issue text.

Assessment

Domain
tooling
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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