Opened 2 years ago

Closed 2 years ago

#30037 closed enhancement (fixed)

Added a construction for BIBDs from symmetric BIBDs

Reported by: gh-Ivo-Maffei Owned by:
Priority: major Milestone: sage-9.2
Component: combinatorial designs Keywords: bibd
Cc: Dima Pasechnik Merged in:
Authors: Ivo Maffei Reviewers: Dima Pasechnik
Report Upstream: N/A Work issues:
Branch: aac95be (Commits, GitHub, GitLab) Commit: aac95beaa3de54a990b06be27b1ca7a529884634
Dependencies: #29959 Stopgaps:

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Description

Given a symmetric (v, k, lambd)-BIBD one can build a (v-k, k-lambd, lambd)-BIBD by removing a block from the former.

For more on BIBDs see https://en.wikipedia.org/wiki/Block_design#Definition_of_a_BIBD_(or_2-design)

Change History (5)

comment:1 Changed 2 years ago by git

Commit: e608ef8346e58e62b0b9eb76358f110511ec5451aac95beaa3de54a990b06be27b1ca7a529884634

Branch pushed to git repo; I updated commit sha1. New commits:

a607693changed docstring
7c4042cMerge branch 'bibd' into recursive_bibd
aac95befixed bug; added tests

comment:2 Changed 2 years ago by gh-Ivo-Maffei

Cc: Dima Pasechnik added
Status: newneeds_review

comment:3 Changed 2 years ago by Dima Pasechnik

to test this recursive builder, it would be nice to have a (maybe internal) function to build all the 2-designs known to Sage with at most v points and with lambda in a given range.

comment:4 Changed 2 years ago by Dima Pasechnik

Reviewers: Dima Pasechnik
Status: needs_reviewpositive_review

Please do what I propose in comment:3 on another ticket. As an example of such a test, cf. _check_database() in sage.graphs.strongly_regular_db.

comment:5 Changed 2 years ago by Volker Braun

Branch: u/gh-Ivo-Maffei/recursive_bibdaac95beaa3de54a990b06be27b1ca7a529884634
Resolution: fixed
Status: positive_reviewclosed
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