2016
01.20

Beyond planarity…

I put my talk from SODA 16 on youtube (the audio quality is not great, but whatever):

  1. Part I: The circle packing theorem.
  2. Part II: The planar separator theorem — the movie.
  3. Part III: Low-density and polynomial expansion graphs.
  4. Part IV: Local search and approximation algorithms.
  5. Part V: Hardness, thesis and open problems.

The slides are available here.

Yalla, bye.

2016
01.17

The art and glory of vector figures/animations…

Poly polypolgon

So, creating a vector animation for talks, once you have a pdf with each page being a frame of the animation is not hard, see here for details.

The question remain, how do we generate such a pdf to begin with? One way is by using a drawing program. Ipe is a good candidate, but creating such figures can be tedious, to put it mildly. In some cases (and you might want to sit before reading the rest of this sentence) there is really no better alternative to… doing some real programming!

Luckily, there is a light graphics library, specifically Cairo, that is happy to output directly to pdf (or svg) files, generating true vector drawings – which are both small, and of higher quality than the “standard” bitmap output (yuck).

Of course, you might want to have an interactive program, with a window and stuff, and output to pdf/svg only when you are happy with the results. Cairo is happy to let you do that – the same drawing code can be used to output to the screen, or to a pdf (or svg). Once you have a pdf, you can easily convert the figure to ipe, and edit the figure directly (using pdftoipe).

As a demonstration of the above, here is the source code of an interactive program I wrote (that I used to generate the above figure). Its a C++ program for linux, using gtk, cairo, and CGAL (because life is too short to implement 2d point class yet again). If this sounds like many libraries one needs, on Debian/Ubiuntu this just requires installing the relevant packages (you would also need the pkg-config package — a nice programming tool). The program is self explanatory as far as what keys do.

And a final comment — to force cairo to output the current image to a new page in the pdf file, one need to use cairo_show_page.

2016
01.11

SODA talk slides

Slides…

You would need acrobat reader to see the animations.

2015
12.13

Word of the day: Trilateration. https://t.co/9V8fC…

Word of the day: Trilateration.
en.wikipedia.org/wiki/Trilatera…

2015
12.12

Kung Fu fight between a man and a cow… https://t…

Kung Fu fight between a man and a cow… youtube.com/watch?v=LxXjsQ…

2015
12.08

How could the ancient Greek mathematicians be so smart, and yet so stupid?

mathpages.com/home/kmath066/…

2015
11.26

Drinking the kool-aid… https://t.co/Z2JpDowwg4

Drinking the kool-aid… en.m.wikipedia.org/wiki/Drinking_…

2015
11.26

The Serial Swatter… https://t.co/Dcixl4yxox

The Serial Swatter… mobile.nytimes.com/2015/11/29/mag…

2015
11.24

who would take away their license to kill?

who would take away their license to kill?

2015
11.19

Red mercury – the WMD every self respecting terror…

Red mercury – the WMD every self respecting terrorist should have. nytimes.com/2015/11/22/mag…

2015
11.15

Conference in Memory of Jiří Matoušek

The conference will be held in the very centre of Prague, Czech Republic, in the historical building Karolinum of Charles University. The date is 23-28th July 2016, which is immediately after European Congress of Mathematics.

More details here.

2015
11.12

iff according to dictionary: “IFF Identification,…

iff according to dictionary: “IFF Identification, Friend or Foe: an electronic system for recognition of friendly aircraft, ships, etc.

2015
11.12

Steven Salaita gets $600,000.

Steven Salaita gets $600,000.

2015
11.07

Bin counting… https://t.co/JCpBNuDXa8

Bin counting… https://t.co/JCpBNuDXa8

CTQv5xrVAAA9CLd

2015
10.27

UIUC CS: New faculty positions

Regular faculty positions: details.
Teaching faculty position: details.

2015
10.27

A Flamingo’s Dream

A Flamingo’s Dream
by Aleksander Wat

Water water water. And nothing but water.
If only an inch of land! An inch of no-matter-what land!
To set one foot on! If only!
We begged the gods for that! All of them!
Water gods, land gods, southern gods, northern gods,
For an inch, a strip, a scrap of any kind of land!
No more than just to support a claw of one foot!
And nothing. Only water. Nothing except water.
Water water water.
If only a speck of land!
There is no salvation.

2015
10.25

“vilifications of the measurements” = “curse of di…

“vilifications of the measurements” = “curse of dimensionality”.

2015
10.24

This boat can handle no more than one ton of passe…

This boat can handle no more than one ton of passengers and the entertainers must weigh less than 1000 lbs. en.wikipedia.org/wiki/Knapsack_…

2015
10.18

Always in lakes among the masterpieces Either star…

Always in lakes among the masterpieces
Either stars or pretty girls are bathing.
(Leopold Staff) leoyankevich.com/archives/256

2015
10.17

Today, 400 years ago: Something happened.

2015
10.14

Do they still give Nobel prizes for discovering ty…

Do they still give Nobel prizes for discovering typos in papers?

Asking for a friend…

2015
10.12

Why Did Anne Frank Hide Like A Coward Instead Of K…

Why Did Anne Frank Hide Like A Coward Instead Of Killing Nazis Dead Like A Real Man?
wonkette.com/594771/why-did…

2015
10.09

A cute deterministic algorithm for min-cut in undi…

A cute deterministic algorithm for min-cut in undirected graphs by Nagamochi & Ibaraki: cs.duke.edu/courses/curren… cs.elte.hu/~frank/cikkek/…

2015
10.06

Jobs, jobs, jobs

UIUC CS is hiring in theory this year. Apply now while supply lasts – we have at least 5 gazillion slots this year in all aspects of computer science, including computational mythology…

CS at Aarhus is also hiring – they are looking for a machine learning person.

2015
10.05

We are so lucky the Afghans didn’t ask the US to drop a nuclear bomb on this hospital.

2015
09.28

Gallery of figures (with source): http://t.co/ZamR…

Gallery of figures (with source): sarielhp.org/p/gallery/

2015
09.27

Nice slides for the ESA 2015 talk (made/presented…

Nice slides for the ESA 2015 talk (made/presented by Kent Quanrud): sarielhp.org/p/14/low_densi…

2015
09.25

A drawing of the levels…

Depiction of the levels in an arrangement of lines
An example of levels (and the k-level in particular) in an arrangement of lines. Here is the ipe source.

2015
09.22

A picture. From http://t.co/lMi9L4bubh http://t.co…

A picture. From sarielhp.org/pictures/x/peo… http://t.co/WEIg34JSgu

CPj_j8wUkAAc1Iy

2015
09.21

Via reddit : he could not stump the trump.

Via reddit : he could not stump the trump.