Macaulay2 / Macaulay2/M2

prune over number fields doesn't return a minimally generated module

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Engine
Dominant language
Macaulay2
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435
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297
Avg merge
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Merged PRs (30d)
11

Description

```
S = QQ[a]/(a^3-a-1)
kk = toField S
M = coker sub(random(S^3, S^{-2,-2}) + random(S^3, S^{-1,-1}) + random(S^3, S^2), kk)
prune M -- BUG!!: first term should be kk^1 on the nose, I would prefer.
```

The last line gives
```
i131 : prune M -- BUG!!: first term should be kk^1 on the nose, I would prefer.

o131 = cokernel | 1 0 |
| 0 1 |
| 0 0 |
```
whereas it should return `kk^1`

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Research direction

Reproduce the issue by running the provided Macaulay2 snippet and inspecting the implementation of prune. Compare the current cokernel output with the expected kk^1 result; done means prune reduces this example to the minimally generated module without changing the reported 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
Active
Clarity
Mostly clear
Newbie friendliness
48/100

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