Macaulay2 / Macaulay2/M2

rank fails over ZZ because codim needs Generic => true

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#3,557 2 comments 0 reactions 0 assignees View on GitHub

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Core
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Macaulay2
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Merged PRs (30d)
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Description

The problem is that there's no way to pass Generic => true to codim via rank.

i1 : R = ZZ[x];

i2 : rank coker vars R
stdio:2:4:(3): error: codim: expected an affine ring (consider Generic=>true to work over QQ)

i3 : options rank

i4 : options \ methods rank

o4 = {0 => null}
     {1 => null}
     {2 => null}
     {3 => null}
     {4 => null}

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First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start by tracing the rank command and its calls to codim, then inspect the options shown for rank and the reported Generic option. Reproduce the ZZ[x] example and verify that rank can forward Generic => true so rank coker vars R succeeds over the non-affine ring.

Written by the indexing model from the issue text.

Assessment

Domain
tooling
Issue type
Bug
Difficulty
3/5
Estimated time
1-2 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
48/100

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