Opened 3 years ago
Closed 3 years ago
#25159 closed defect (fixed)
Fix connected sum of knots
Reported by: | mmarco | Owned by: | |
---|---|---|---|
Priority: | major | Milestone: | sage-8.3 |
Component: | algebraic topology | Keywords: | connected_sum, knot |
Cc: | slelievre | Merged in: | |
Authors: | Miguel Marco | Reviewers: | Samuel Lelièvre |
Report Upstream: | N/A | Work issues: | |
Branch: | d8cb5c1 (Commits, GitHub, GitLab) | Commit: | d8cb5c1fd9b25a4b9d5c089dddca1c9db4010245 |
Dependencies: | Stopgaps: |
Description (last modified by )
As pointed in https://ask.sagemath.org/question/41985/connected-sum-of-knots/ the connected sum of knots is not correctly computed.
Before this ticket, the connected sum of the trefoil knot with itself is incorrect, and computing the connected sum with a third trefoil knot fails:
sage: c = Knot.connected_sum sage: B = BraidGroup(2) sage: t = Knot(B([1, 1, 1])); t Knot represented by 3 crossings sage: tt = c(t, t); tt Knot represented by 7 crossings sage: tt_t = c(tt, t); tt_t Traceback (most recent call last) ... ValueError: the input has more than 1 connected component sage: t_tt = c(t, tt); t_tt Traceback (most recent call last) ... ValueError: generators not in the group
After this ticket, these problems are fixed:
sage: c = Knot.connected_sum sage: B = BraidGroup(2) sage: t = Knot(B([1, 1, 1])); t Knot represented by 3 crossings sage: tt = c(t, t); tt Knot represented by 6 crossings sage: t_tt = c(t, tt); t_tt Knot represented by 9 crossings sage: tt_t = c(tt, t); tt_t Knot represented by 9 crossings sage: t_tt = tt_t True
Change History (10)
comment:1 Changed 3 years ago by
- Branch set to u/mmarco/connected_sum_of_knots_is_incorrect
comment:2 Changed 3 years ago by
- Commit set to d8cb5c1fd9b25a4b9d5c089dddca1c9db4010245
- Status changed from new to needs_review
comment:3 Changed 3 years ago by
- Keywords connected_sum knot added
- Status changed from needs_review to positive_review
This makes connected_sum
correct (and a little faster it seems!).
comment:4 Changed 3 years ago by
- Description modified (diff)
- Summary changed from Connected sum of knots is incorrect to Fix connected sum of knots
comment:5 Changed 3 years ago by
- Description modified (diff)
comment:6 Changed 3 years ago by
- Reviewers set to Samuel Lelièvre
comment:7 Changed 3 years ago by
- Milestone changed from sage-8.2 to sage-8.3
comment:8 Changed 3 years ago by
Why hasn't this been merged?
comment:9 Changed 3 years ago by
- Reviewers changed from Samuel Lelièvre to Samuel Lelièvre
There was an invisible unicode in the reviewer name
comment:10 Changed 3 years ago by
- Branch changed from u/mmarco/connected_sum_of_knots_is_incorrect to d8cb5c1fd9b25a4b9d5c089dddca1c9db4010245
- Resolution set to fixed
- Status changed from positive_review to closed
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Compute the connected sum from the oriented gauss code