Tag Archive - mathematics
Using Axiom with vi keystrokes
Maple’s command line interface honors vi keystrokes so I thought I should have those in Axiom too. Here’s a short recipe for that:
First of all, put the following line in your $HOME/.inputrcfile:
set editing-mode vi
This will tell the readline library to use vi-style editing by default.
After this, you will have to install rlwrap if you don’t have it on your system.
Now invoke Axiom with the following:
rlwrap -c -f /usr/local/axiom/mnt/fedora5/lib/command.list axiom -noclef
Note that you may have to replace the argument to the -f option with the location of command.list on your system (this will give you Axiom-specific completions).
That’s all!
Introduction to the lambda calculus
A Brave New Hope briefly reviews an interesting text on the lambda calculus. This reminded me of one of the books that got me started in functional programming: An introduction to functional programming through lambda calculus by Greg Michaelson. It is an enjoyable and fast-paced text which I’d recommend if you’re looking for a good introduction to the subject.
Lost integer sequence
4, 8, 15, 16, 23, 42. These numbers are becoming more important in each episode of Lost and Marcus Dicander has submitted them to the On-Line Encyclopedia of Integer Sequences.
I don’t know (yet) what those numbers are supposed to mean in the show but it seems to me that the last two of them are a tribute to William Burrough’s 23 enigma and Douglas Adams’ answer to The Ultimate Question Of Life, the Universe, and Everything respectively.
Internet topology modeling
In this lecture, Walter Willinger goes into the difficulties of Internet topology modeling (on the IP level).
Accurate models of how the Internet works give insight into where its weakest links are located and how to simulate the network’s behavior under certain circumstances.
Part of the lecture’s data was acquired using traceroute and thorny technical details like detecting aliased IPs and load balancers were skipped.
Some highlights of the talk are:
- Usage of economic models and current technological constraints to model the network (the resulting topology should be efficient).
- Pitfalls of paying too much attention to power laws.
- Differences between the real Internet and scale-free networks.
I believe some of the points the author makes could be applied as well to overlay (P2P) networks.
Further links:
Mathematicians improve epilepsy treatment’s success
Mathematicians from the Johannes Kepler Univerity at Linz, Austria and the Max Planck Institute in Leipzig, Germany have found a way to compute the location of braincells responsible for epilepsy in five hours. Before this, it would take weeks or even months to perform this task increasing the chance of failure in a surgical operation.
Here are some references to this research:
- Ulrich Langer, research director for the initiative
- A parallel algebraic multigrid solver for finite element method based source localization in the human brain. Related article regarding finite element methods applied to neurology