Macaulay2 / Macaulay2/M2

isWellDefined for ring maps

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Core
Dominant language
Macaulay2
Stars
435
Forks
297
Avg merge
4d 20h
Merged PRs (30d)
11

Description

I think `isWellDefined` is ignoring the coefficient ring (when one is present) and incorrectly returning `true`.

For example,`isWellDefined map(ZZ,(ZZ/5))` tells me correctly that this map is not well-defined, but `isWellDefined map(ZZ[x],(ZZ/5)[x])` returns true.

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  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Locate the implementation of isWellDefined and map, then reproduce the two examples from the issue in Macaulay2. Trace how coefficient rings are handled and add a regression test covering the polynomial-ring case; done means the second example is no longer reported as well-defined.

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
Stale
Clarity
Mostly clear
Newbie friendliness
45/100

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