A new version of SnapPy, a program for studying the topology and geometry of 3-manifolds, is available. Added features include a census of Platonic manifolds, rigorous computation of cusp translations, and substantial improvements to its link diagram component.

## May 24, 2016

## March 22, 2015

### SnapPy 2.3 released

Marc Culler and I are pleased to announce version 2.3 of SnapPy. New features include:

- Major improvements to the link and planar diagram component, including link simplification, random links, and better documentation.
- Basic support for spun normal surfaces.
- New extra features when used inside of Sage:
- HIKMOT-style rigorous verification of hyperbolic structures,

contributed by Matthias Goerner. - Many basic knot/link invariants, contributed by Robert

Lipschitz and Jennet Dickinson. - Sage-specific functions are now more easily accessible as

methods of Manifold and better documented. - Improved number field recognition, thanks to Matthias.

- HIKMOT-style rigorous verification of hyperbolic structures,
- Better compatibility with OS X Yosemite and Windows 8.1.
- Development changes:
- Major source code reorganization/cleanup.
- Source code repository moved to Bitbucket.
- Python modules now hosted on PyPI, simplifying installation.

All available at the usual place.

## March 9, 2015

### Complex hyperbolic geometry of knot complements

This morning there was a paper which caught my eye:

Deraux, M. & Falbel, E. 2015 Complex hyperbolic geometry of the figure-eight knot.

Geometry & Topology19, 237–293.

In it, the authors study a very different geometric structure for the figure-eight knot complement, as the manifold at infinity of a complex hyperbolic orbifold. (more…)

## March 2, 2014

### SnapPy 2.1: Now with extra precision!

Marc Culler and I released SnapPy 2.1 today. The main new feature is the ManifoldHP variant of Manifold which does all floating-point calculations in quad-double precision, which has four times as many significant digits as the ordinary double precision numbers used by Manifold. More precisely, numbers used in ManifoldHP have 212 bits for the mantissa/significand (roughly 63 decimal digits) versus 53 bits with Manifold.

## November 26, 2013

### What’s Next? A conference in question form

Mark your calendars now: in June 2014, Cornell University will host “What’s Next? The mathematical legacy of Bill Thurston”. It looks like it will be a very exciting event, see the (lightly edited) announcement from the organizers below the fold.

## September 30, 2013

### SnapPy 2.0 released

Marc Culler and I pleased to announce version 2.0 of SnapPy, a program for studying the topology and geometry of 3-manifolds. Many of the new features are graphical in nature, so we made a new tutorial video to show them off. Highlights include

(more…)

## April 23, 2013

### When are two hyperbolic 3-manifolds homeomorphic?

A preprint of Lins and Lins appeared on the arXiv today, posing a challenge [LL]. In this post, I’m going to discuss that challenge, and describe a recent algorithm of Scott–Short [SS] which may point towards an answer.

**The Lins–Lins challenge**

The theory of 3-manifolds is now very advanced, and we can even say in a certain sense that we understand ‘all’ 3-manifolds (as I discussed in an earlier post). But that understanding is very theoretical; the Lins–Lins challenge is to put this theory into practice.

They ask: ‘Are the two closed, hyperbolic 3-manifolds given by Dehn surgery on the following two framed links homeomorphic?’

(I’ve taken the liberty of copying the diagrams from their paper.)

## April 20, 2013

### The next big thing in quantum topology?

The place to be in May for a quantum topologist is Vietnam. After some wonderful-sounding mini-courses in Hanoi, the party with move to Nha Trang (dream place to visit) for a quantum topology conference.

I’d like to tell you very briefly about some exciting developments which I expect will be at the centre of the Nha Trang conference, and which I expect may significantly effect the landscape in quantum topology. The preprint in question is -Efficient triangulations and the index of a cusped hyperbolic -manifold by Garoufalidis, Hodgson, Rubinstein, and Segerman (with a list of authors like that, you know it’s got to be good!). (more…)

## April 6, 2013

### New connection between geometric and quantum realms

A paper by Thomas Fiedler has just appeared on arXiv, describing a new link between geometric and quantum topology of knots. http://arxiv.org/abs/1304.0970

This is big news!! (more…)

## February 5, 2013

### Wise’s CBMS Lecture Notes on Cube Complexes

This fall, the topology group at OSU is reading through Dani Wise’s lecture notes on cube complexes, based on his series of talks at the CBMS-NSF conference back in 2011. Henry Wilton and Daniel Moskovich have written on this blog about Wise’s work and its role in the proof of the Virtual Haken Conjecture. This is just a quick note to say how impressed I’ve been with the lecture notes. They start from the very beginning, include a lot of good examples and have proved to be very accessible for all of us non-experts (which includes me).

It’s just too bad that Wise’s notes are no longer available on the conference web page. (Now that a paper copy is available from the AMS, the PDF file has been replaced with a note saying that the editor insisted they be taken down.) You can still e-mail Dani Wise to request a copy, but I expect that some people (such as beginning graduate students) might be reluctant to e-mail someone they don’t know like this. I can assure you, he was very gracious when I asked him for a copy and seems to be very eager to distribute the notes widely. But, if you have any thoughts on how the PDF file could be distributed more efficiently, I would love to hear about it in the comments.