# Sage Days 49 Coding Sprint Projects

**For the main Sage Days 49 page go** here

Below is a list of proposed projects. Please edit and add your projects!

### Combinatorics

Implementing Stanley chromatic symmetric function for posets

Mathieu, Eric, Alejandro, Chris, Nathann, Yan

Implementing boards for rook placements, Le diagrams (#14127)

- implementing Le diagrams
- include CombinatorialMaps if possible
- adding documentation and doctests

Alejandro, Kevin (testing/doctests), Bruce, Salvatore, Emily, Federico

Flow polytopes from permutation matrices and alternating sign matrices (#14654)

Jessica, Alejandro, Nathann, Emily, Laura

Implementation of k-tableaux and k-charge (#12250, #14776)

Anne, Mike, Tom D, Nate, Avi

Combinatorial actions and orbit averages on posets, order polytopes, and rational functions

Tom Roby, Darij, Jessica, Kevin, Emma, Emily

Multivariate power series / lazy

Marguerite, Mathieu, Florent, Marc

Hypergraph visualization

Nathann

Combinatorial Species

Martin Rubey, Bruce, Mike, Florent, Tom D., Marguerite Thursday and Friday only

- code cleanup
- generation of unlabelled objects for composition and functorial composition via a group action framework
- multisort species (multivariate formal power series would be useful for that)
- add code by Andrew for Gamma-species
- support operations from symmetric function code for cycle index series

Conclude OEIS ticket #10358 (rebase after #13701, last doctests, and make urls clickable from the notebook

ThierryMonteil, Eric, Chris, Salvatore

More switches from CombinatorialClass to category framework

Travis, Mike, Anne, Mathieu, Simon, Florent

Implement LaTeX options for parking functions

Mike, Jean-Baptiste, Tom D.

Implement composition tableaux as an enumerated set (finite? with grading?)

Mike, Chris, Jessica, Austin, Tom D., Elizabeth

Beef up NSym/QSym functionality - dual bases, quasi-Schur and dual's, basis by Pieri rule, map to free algebra, P-partitions (#14136), Hazewinkel's lambda-Lyndon basis, quasi-Schurs, expansion in non commutative variables, ...

Mike, Matthieu Deneufchâtel, Darij, Chris, Simon, Anne, Meesue

Ribbon graphs

Bruce, Emily, Chris

Finish affine symmetric group patch (#12940) Done!

Tom D., Chris, Anne

Implement BWSym and related Hopf algebras

Olivier Mallet, Ali Chouria, Jean-Baptiste, Florent, Mike

Posets - Close outstanding tickets, optimize counting linear extensions, add poset examples (absolute order on symmetric group, etc.)

Kevin, Nathann, Mathieu, Florent, Anne, Jessica, Tom R., Darij

Infinite root system: construction, display

Vivien, Nicolas, Salvatore, William, Elizabeth, Ben, Laura

### Representation Theory

Finalize non-symmetric Macdonald polynomial patch (#14102)

Anne, Nicolas, Mike

Implement monomial crystals (#14759) Done and merged!

Ben, Travis, Arthur, Nicolas, Anne

Refactor and speedup of all crystals code (#14516 Done!, #14686, more to come)

Travis, Ben, Nicolas, Anne

Make progress on fixing/reviewing rigged configurations patches (#13871, #13838, #13872)

Anne, Travis, Chris

Representations of quivers and quiver algebras: Finish refactoring Jim's code (#12630)

Simon, Salvatore, Nicolas, Aladin, Florent, Ben, Tom R., Mathieu

### Hyperplane arrangements

Tom, William, Vivien, Nathann, Steven, Alejandro

### Categories and infrastructure

Nicolas, Simon, Travis, Florent

- Review #10963 more functorial constructions
- Review #11111 finite dimensional modules
- Nested class name mangling: Understand why building the pdf documentation hangs with the patch from #9107
- Plan the follow ups

### Documentation

Reorganize combinat documentation

Travis, Nathann, Florent, Mike, Simon, Nicolas, Anne

Update French translation of the tutorial

Marc

### Teaching

Going through "Topics in Algebraic Combinatorics" and see how much is in Sage / would be useful for teaching

Tom^2, Alejandro, Elizabeth, Jessica, Aladin, Austin, Laura

Update/fix doctests from the French Sage book

Marc, Nathann, Nicolas, Guillaume: fix the web version to make sure its 100% consistent with the paper version

Cleanup Map-Reduce & other parallelization tools in Sage

Florent, Jean-Baptiste, Matthieu

### Other

Finish CFF #14567 review (ThierryMonteil)

Trac-ify some of the bugs found via ask.sagemath.org and discuss about better integration between those two useful tools (ThierryMonteil)

Work on making RIF and CIF more reliable (ThierryMonteil)

Add parallel cloning to Sage Debian Live USB key (ThierryMonteil)

FindStat work

Travis, Viviane, Chris, Jessica, Jean-Baptiste