# Sage Days 91: Open Source Computation and Algebraic Surfaces (Sept. 29 - Oct. 1, 2017)

Location: Banff International Research Station.

## Schedule

https://www.birs.ca/events/2017/2-day-workshops/17w2677/schedule

## Projects

Feel free to add suggestions

Please add "sd91" as a keyword to any tickets you are working on during this Sage Days so they show up in this list: sd91 Tickets

**Lattice related projects**

fix vector matrix multiplication for free module elements #23576

fix .annihilator() for the trivial abelian group #22720

use the inner_product_matrix for module comparison #23915

implement finite bilinear/quadratic forms and make sure that the discriminant group has one #23699

- implement QQ/ZZ , QQ/2ZZ or QQ/nZZ as abelian groups. This is where finite quadratic/bilinear forms have values
- implement a class for (subgroups of) the orthogonal group of a finite bilinear/quadratic form and an algorithm to compute it
- diagonalization and isomorphism testing for finite quadratic/bilinear forms
- create a genus from a signature pair and a finite quadratic form
- create a finite quadratic form from a genus
a latex representation for the genus using the Conway Sloane genus symbols #23916

- a base class for the orthogonal group of a lattice
- a method to compute the orthogonal group of a positive definite lattice
expose more of Jeffery Hein's lattice code than is currently being used for modular forms 23342

**Point counting and zeta function projects**

hypergeometric motives #23671

get Edgar Costa's code for zeta functions of projective hypersurfaces into Sage #23863

package Sebastian Pancratz's code for deformation computation of zeta functions #20265

implement a (rigorous, sane) test for Weil polynomials. More ambitious: get this code for exhausting over Weil polynomials into Sage

Add Malcolm Kotok's code for zeta functions using the Sperber-Voight algorithm to Sage: #19865, http://hdl.handle.net/1802/30832

## Tickets needing review

## To prepare for the workshop

Before the workshop, we recommend opening a Sage trac account and completing the Code Academy modules on Python and Git. If you like you may download and install the latest version of the source code of Sage, though we hope to arrange installations on a CoCalc server.

## Possible Interest Groups

Lattices: Simon Brandhorst, Amy Feaver, Andreas Malmendier, David Roe, Ichiro Shimada

Zeta functions (Monsky-Washnitzer cohomology): Jen Balakrishnan, Edgar Costa, Kiran Kedlaya

Zeta functions (Dwork cohomology): Anastassia Etropolski, Heidi Goodson, Tony Várilly-Alvarado, Ursula Whitcher

People of many interests: Jen Berg, Renate Scheidler, Mckenzie West, David Zureick-Brown, Lenny Taelman