betti with degree 0 variables
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Core
- Dominant language
- Macaulay2
- Stars
- 435
- Forks
- 297
- Avg merge
- 4d 20h
- Merged PRs (30d)
- 11
Description
Macaulay2 seems to give strange betti tables for modules over rings with variables of degree 0.
i1 : S = ZZ/101[x,y,Degrees => {{0},{1}}]
o1 = S
o1 : PolynomialRing
i2 : M = comodule ideal y
o2 = cokernel | y |
1
o2 : S-module, quotient of S
i3 : betti M
0 1
o3 = total: 1 1
-1: . 1
0: 1 .
o3 : BettiTally
i4 : F = prune res M
1 1
o4 = S <-- S <-- 0
0 1 2
o4 : ChainComplex
i5 : degrees F_1
o5 = {{1}}
o5 : List
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First steps
- Read the whole issue, then the project's contributing guide.
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Research direction
Reproduce the example at the betti and res entry points using S, M, and F from the issue, then compare betti M with degrees F_1. Trace how degree-0 variables are handled in the Betti-table and resolution code. Done means the inconsistent behavior is corrected and covered by a regression test for this example.
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