Opened 5 years ago
Closed 5 years ago
#25159 closed defect (fixed)
Fix connected sum of knots
Reported by: | mmarco | Owned by: | |
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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 5 years ago by
Branch: | → u/mmarco/connected_sum_of_knots_is_incorrect |
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comment:2 Changed 5 years ago by
Commit: | → d8cb5c1fd9b25a4b9d5c089dddca1c9db4010245 |
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Status: | new → needs_review |
comment:3 Changed 5 years ago by
Keywords: | connected_sum knot added |
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Status: | needs_review → positive_review |
This makes connected_sum
correct (and a little faster it seems!).
comment:4 Changed 5 years ago by
Description: | modified (diff) |
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Summary: | Connected sum of knots is incorrect → Fix connected sum of knots |
comment:5 Changed 5 years ago by
Description: | modified (diff) |
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comment:6 Changed 5 years ago by
Reviewers: | → Samuel Lelièvre |
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comment:7 Changed 5 years ago by
Milestone: | sage-8.2 → sage-8.3 |
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comment:9 Changed 5 years ago by
Reviewers: | Samuel Lelièvre → Samuel Lelièvre |
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There was an invisible unicode in the reviewer name
comment:10 Changed 5 years ago by
Branch: | u/mmarco/connected_sum_of_knots_is_incorrect → d8cb5c1fd9b25a4b9d5c089dddca1c9db4010245 |
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Resolution: | → fixed |
Status: | positive_review → closed |
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New commits:
Compute the connected sum from the oriented gauss code