`isHomogeneous` incorrect for a Weyl algebra
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- Dominant language
- Macaulay2
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Description
```
i1 : W1 = QQ[x,dx,WeylAlgebra=>{x=>dx}]
o1 = W1
o1 : PolynomialRing, 1 differential variable(s)
i2 : W2 = QQ[x,dx,WeylAlgebra=>{x=>dx},Degrees=>{1,-1}]
o2 = W2
o2 : PolynomialRing, 1 differential variable(s)
i3 : assert not isHomogeneous 0_W1 -- correct
i4 : assert isHomogeneous 0_W2
i5 : assert not isHomogeneous W1 -- fails
stdio:5:1:(3): error: assertion failed
i6 : assert isHomogeneous W2
```
This bug was introduced on 2020-11-06 via
```
isHomogeneous PolynomialRing := R -> true
```
in `m2/polyrings.m2`.
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First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start in m2/polyrings.m2 at the isHomogeneous PolynomialRing method introduced on 2020-11-06, then reproduce the W1 and W2 assertions from the issue in Macaulay2. Done means the homogeneous checks distinguish the two Weyl algebra gradings as shown, while the zero-element checks continue to pass.
Written by the indexing model from the issue text.
Assessment
- Domain
- backend
- Issue type
- Bug
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100