Opened 3 years ago
Closed 2 years ago
#25922 closed defect (duplicate)
Bug in is_postcritically_finite
Reported by: | bellatobin | Owned by: | |
---|---|---|---|
Priority: | minor | Milestone: | sage-duplicate/invalid/wontfix |
Component: | dynamics | Keywords: | Post-critically finite |
Cc: | Merged in: | ||
Authors: | Reviewers: | ||
Report Upstream: | N/A | Work issues: | |
Branch: | Commit: | ||
Dependencies: | Stopgaps: |
Description (last modified by )
is_postcritically_finite returns false for certain PCF functions.
Below is an example of the code in which PCF fails. I first applied is_postcritically_finite to the function, which output False and then found the finite critical orbits.
sage: P1.<x,y> = ProjectiveSpace(QQ,1); sage: H = P1.Hom(P1); sage: a = .5; c = 1.5; sage: f = H([-2*a*x^3+3*a*x^2*y+c*y^3,y^3]); sage: f.is_postcritically_finite() False sage: f.critical_points() [(0 : 1), (1 : 0), (1 : 1)] sage: P = P1(0,1) sage: f(P) (3/2 : 1) sage: f(f(P)) (3/2 : 1) sage: Q = P1(1,1) sage: f(Q) (2 : 1) sage: f(f(f(Q))) (2 : 1)
Change History (5)
comment:1 Changed 3 years ago by
- Description modified (diff)
comment:2 Changed 3 years ago by
- Milestone changed from sage-8.4 to sage-duplicate/invalid/wontfix
comment:3 Changed 3 years ago by
- Status changed from new to needs_review
comment:4 Changed 3 years ago by
- Status changed from needs_review to positive_review
comment:5 Changed 2 years ago by
- Resolution set to duplicate
- Status changed from positive_review to closed
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oops. I missed the fact this was already opened as a ticket. I pushed the fix to #25939. The issue is in canonical height, not in is_postcritically_finite.
If you agree that 25939, fixes the issue in is_postcritically_finite, then mark this as positive-review so that it gets closed as 'duplicate'. If there are still further issues with is_pcf, then we can revisit this ticket for those fixes.