graphs: add implementation of slice decomposition via an extended LexBFS algorithm #38299
Conversation
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
|
Documentation preview for this PR (built with commit 0d26f30; changes) is ready! 🎉 |
dcoudert
suggested changes
Jul 2, 2024
dcoudert
suggested changes
Jul 3, 2024
done |
|
I found a bug in the |
vbraun
pushed a commit
to vbraun/sage
that referenced
this pull request
Sep 6, 2024
…ia an extended LexBFS algorithm
<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes sagemath#12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes sagemath#12345". -->
This PR implements a new graph decomposition: slice decomposition.
Precise definition and a description of the algorithm can be found in
[TCHP2008 (section 3.2 & 3.3)](https://arxiv.org/pdf/0710.3901v3).
I implemented a new method (only for undirected graphs) called
`slice_decomposition`. It returns a new class `SliceDecompostion`, with
methods to retrieve the information about the computed slice
decomposition.
The code is in a new file:
`graph_decompositions/slice_decomposition.pyx`.
The actual computation is done with a new function called
`extended_lex_BFS` which only works for undirected graphs. It is very
close to the previous `lex_BFS_fast_short_digraph` from
`traversals.pyx`, the difference being that the new function works with
the `CGraph` directly (no conversion needed to `short_digraph` anymore)
and it computes more information (lexicographic labels and length of
x-slices). The complexity of the two algorithms are the same.
So I removed `lex_BFS_fast_short_digraph` from `traversals.pyx` and
used `extended_lex_BFS` instead for the "fast" version of the `lex_BFS`
method.
I took the opportunity to factorize the code between `lex_BFS` ("slow"
version), `lex_DFS`, `lex_UP` and `lex_DOWN`
in `traversals.pyx`: there is no more conversion to `short_digraph` and
they all call the same common function
(remark: i was not able to put the doc in common, so there is still some
repetition between the doc of these methods)
### 📝 Checklist
<!-- Put an `x` in all the boxes that apply. -->
- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [x] I have created tests covering the changes.
- [x] I have updated the documentation and checked the documentation
preview.
### ⌛ Dependencies
<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
URL: sagemath#38299
Reported by: cyrilbouvier
Reviewer(s): cyrilbouvier, David Coudert
|
On 32-bit: |
github-actions
bot
added
s: needs review
and removed
s: positive review
s: needs work
labels
Should be fixed by 0d26f30 |
dcoudert
reviewed
Sep 7, 2024
| sage: P3 = graphs.PathGraph(3) | ||
| sage: SD1 = P3.slice_decomposition(initial_vertex=0) | ||
| sage: SD2 = P3.slice_decomposition(initial_vertex=2) | ||
| sage: len({SD1: 1, SD2: 2}) # indirect doctest |
There was a problem hiding this comment.
This seems ok, but why not simply hash(SD1) != hash(SD2) ?
There was a problem hiding this comment.
I got the idea by looking at other doctests for other __hash__ methods.
By thinking a little about it, there is a nonzero probability that there exists an architecture where the hashes could be equal. But as keys of a dict are compare via __eq__ if they have the same hashes, even in this (very very) improbable case the test should pass.
There was a problem hiding this comment.
You are right. Thank you for the clarification.
vbraun
pushed a commit
to vbraun/sage
that referenced
this pull request
Sep 8, 2024
…ia an extended LexBFS algorithm
<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes sagemath#12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes sagemath#12345". -->
This PR implements a new graph decomposition: slice decomposition.
Precise definition and a description of the algorithm can be found in
[TCHP2008 (section 3.2 & 3.3)](https://arxiv.org/pdf/0710.3901v3).
I implemented a new method (only for undirected graphs) called
`slice_decomposition`. It returns a new class `SliceDecompostion`, with
methods to retrieve the information about the computed slice
decomposition.
The code is in a new file:
`graph_decompositions/slice_decomposition.pyx`.
The actual computation is done with a new function called
`extended_lex_BFS` which only works for undirected graphs. It is very
close to the previous `lex_BFS_fast_short_digraph` from
`traversals.pyx`, the difference being that the new function works with
the `CGraph` directly (no conversion needed to `short_digraph` anymore)
and it computes more information (lexicographic labels and length of
x-slices). The complexity of the two algorithms are the same.
So I removed `lex_BFS_fast_short_digraph` from `traversals.pyx` and
used `extended_lex_BFS` instead for the "fast" version of the `lex_BFS`
method.
I took the opportunity to factorize the code between `lex_BFS` ("slow"
version), `lex_DFS`, `lex_UP` and `lex_DOWN`
in `traversals.pyx`: there is no more conversion to `short_digraph` and
they all call the same common function
(remark: i was not able to put the doc in common, so there is still some
repetition between the doc of these methods)
### 📝 Checklist
<!-- Put an `x` in all the boxes that apply. -->
- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [x] I have created tests covering the changes.
- [x] I have updated the documentation and checked the documentation
preview.
### ⌛ Dependencies
<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
URL: sagemath#38299
Reported by: cyrilbouvier
Reviewer(s): cyrilbouvier, David Coudert
vbraun
pushed a commit
to vbraun/sage
that referenced
this pull request
Sep 10, 2024
…ia an extended LexBFS algorithm
<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes sagemath#12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes sagemath#12345". -->
This PR implements a new graph decomposition: slice decomposition.
Precise definition and a description of the algorithm can be found in
[TCHP2008 (section 3.2 & 3.3)](https://arxiv.org/pdf/0710.3901v3).
I implemented a new method (only for undirected graphs) called
`slice_decomposition`. It returns a new class `SliceDecompostion`, with
methods to retrieve the information about the computed slice
decomposition.
The code is in a new file:
`graph_decompositions/slice_decomposition.pyx`.
The actual computation is done with a new function called
`extended_lex_BFS` which only works for undirected graphs. It is very
close to the previous `lex_BFS_fast_short_digraph` from
`traversals.pyx`, the difference being that the new function works with
the `CGraph` directly (no conversion needed to `short_digraph` anymore)
and it computes more information (lexicographic labels and length of
x-slices). The complexity of the two algorithms are the same.
So I removed `lex_BFS_fast_short_digraph` from `traversals.pyx` and
used `extended_lex_BFS` instead for the "fast" version of the `lex_BFS`
method.
I took the opportunity to factorize the code between `lex_BFS` ("slow"
version), `lex_DFS`, `lex_UP` and `lex_DOWN`
in `traversals.pyx`: there is no more conversion to `short_digraph` and
they all call the same common function
(remark: i was not able to put the doc in common, so there is still some
repetition between the doc of these methods)
### 📝 Checklist
<!-- Put an `x` in all the boxes that apply. -->
- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [x] I have created tests covering the changes.
- [x] I have updated the documentation and checked the documentation
preview.
### ⌛ Dependencies
<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
URL: sagemath#38299
Reported by: cyrilbouvier
Reviewer(s): cyrilbouvier, David Coudert
vbraun
pushed a commit
to vbraun/sage
that referenced
this pull request
Sep 12, 2024
…ia an extended LexBFS algorithm
<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes sagemath#12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes sagemath#12345". -->
This PR implements a new graph decomposition: slice decomposition.
Precise definition and a description of the algorithm can be found in
[TCHP2008 (section 3.2 & 3.3)](https://arxiv.org/pdf/0710.3901v3).
I implemented a new method (only for undirected graphs) called
`slice_decomposition`. It returns a new class `SliceDecompostion`, with
methods to retrieve the information about the computed slice
decomposition.
The code is in a new file:
`graph_decompositions/slice_decomposition.pyx`.
The actual computation is done with a new function called
`extended_lex_BFS` which only works for undirected graphs. It is very
close to the previous `lex_BFS_fast_short_digraph` from
`traversals.pyx`, the difference being that the new function works with
the `CGraph` directly (no conversion needed to `short_digraph` anymore)
and it computes more information (lexicographic labels and length of
x-slices). The complexity of the two algorithms are the same.
So I removed `lex_BFS_fast_short_digraph` from `traversals.pyx` and
used `extended_lex_BFS` instead for the "fast" version of the `lex_BFS`
method.
I took the opportunity to factorize the code between `lex_BFS` ("slow"
version), `lex_DFS`, `lex_UP` and `lex_DOWN`
in `traversals.pyx`: there is no more conversion to `short_digraph` and
they all call the same common function
(remark: i was not able to put the doc in common, so there is still some
repetition between the doc of these methods)
### 📝 Checklist
<!-- Put an `x` in all the boxes that apply. -->
- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [ ] I have linked a relevant issue or discussion.
- [x] I have created tests covering the changes.
- [x] I have updated the documentation and checked the documentation
preview.
### ⌛ Dependencies
<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
URL: sagemath#38299
Reported by: cyrilbouvier
Reviewer(s): cyrilbouvier, David Coudert
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This PR implements a new graph decomposition: slice decomposition. Precise definition and a description of the algorithm can be found in TCHP2008 (section 3.2 & 3.3).
I implemented a new method (only for undirected graphs) called
slice_decomposition. It returns a new classSliceDecompostion, with methods to retrieve the information about the computed slice decomposition.The code is in a new file:
graph_decompositions/slice_decomposition.pyx.The actual computation is done with a new function called
extended_lex_BFSwhich only works for undirected graphs. It is very close to the previouslex_BFS_fast_short_digraphfromtraversals.pyx, the difference being that the new function works with theCGraphdirectly (no conversion needed toshort_digraphanymore) and it computes more information (lexicographic labels and length of x-slices). The complexity of the two algorithms are the same.So I removed
lex_BFS_fast_short_digraphfromtraversals.pyxand usedextended_lex_BFSinstead for the "fast" version of thelex_BFSmethod.I took the opportunity to factorize the code between
lex_BFS("slow" version),lex_DFS,lex_UPandlex_DOWNin
traversals.pyx: there is no more conversion toshort_digraphand they all call the same common function(remark: i was not able to put the doc in common, so there is still some repetition between the doc of these methods)
📝 Checklist
⌛ Dependencies