Andrew Cooke | Contents | Latest | RSS | Previous | Next

C[omp]ute

Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

Personal Projects

Choochoo Training Diary

Last 100 entries

Surprise Paradox; [Books] Good Author List; [Computing] Efficient queries with grouping in Postgres; [Computing] Automatic Wake (Linux); [Computing] AWS CDK Aspects in Go; [Bike] Adidas Gravel Shoes; [Computing, Horror] Biological Chips; [Books] Weird Lit Recs; [Covid] Extended SIR Models; [Art] York-based Printmaker; [Physics] Quantum Transitions are not Instantaneous; [Computing] AI and Drum Machines; [Computing] Probabilities, Stopping Times, Martingales; bpftrace Intro Article; [Computing] Starlab Systems - Linux Laptops; [Computing] Extended Berkeley Packet Filter; [Green] Mainspring Linear Generator; Better Approach; Rummikub Solver; Chilean Poetry; Felicitations - Empowerment Grant; [Bike] Fixing Spyre Brakes (That Need Constant Adjustment); [Computing, Music] Raspberry Pi Media (Audio) Streamer; [Computing] Amazing Hack To Embed DSL In Python; [Bike] Ruta Del Condor (El Alfalfal); [Bike] Estimating Power On Climbs; [Computing] Applying Azure B2C Authentication To Function Apps; [Bike] Gearing On The Back Of An Envelope; [Computing] Okular and Postscript in OpenSuse; There's a fix!; [Computing] Fail2Ban on OpenSuse Leap 15.3 (NFTables); [Cycling, Computing] Power Calculation and Brakes; [Hardware, Computing] Amazing Pockit Computer; Bullying; How I Am - 3 Years Post Accident, 8+ Years With MS; [USA Politics] In America's Uncivil War Republicans Are The Aggressors; [Programming] Selenium and Python; Better Walking Data; [Bike] How Fast Before Walking More Efficient Than Cycling?; [COVID] Coronavirus And Cycling; [Programming] Docker on OpenSuse; Cadence v Speed; [Bike] Gearing For Real Cyclists; [Programming] React plotting - visx; [Programming] React Leaflet; AliExpress Independent Sellers; Applebaum - Twilight of Democracy; [Politics] Back + US Elections; [Programming,Exercise] Simple Timer Script; [News] 2019: The year revolt went global; [Politics] The world's most-surveilled cities; [Bike] Hope Freehub; [Restaurant] Mama Chau's (Chinese, Providencia); [Politics] Brexit Podcast; [Diary] Pneumonia; [Politics] Britain's Reichstag Fire moment; install cairo; [Programming] GCC Sanitizer Flags; [GPU, Programming] Per-Thread Program Counters; My Bike Accident - Looking Back One Year; [Python] Geographic heights are incredibly easy!; [Cooking] Cookie Recipe; Efficient, Simple, Directed Maximisation of Noisy Function; And for argparse; Bash Completion in Python; [Computing] Configuring Github Jekyll Locally; [Maths, Link] The Napkin Project; You can Masquerade in Firewalld; [Bike] Servicing Budget (Spring) Forks; [Crypto] CIA Internet Comms Failure; [Python] Cute Rate Limiting API; [Causality] Judea Pearl Lecture; [Security, Computing] Chinese Hardware Hack Of Supermicro Boards; SQLAlchemy Joined Table Inheritance and Delete Cascade; [Translation] The Club; [Computing] Super Potato Bruh; [Computing] Extending Jupyter; Further HRM Details; [Computing, Bike] Activities in ch2; [Books, Link] Modern Japanese Lit; What ended up there; [Link, Book] Logic Book; Update - Garmin Express / Connect; Garmin Forerunner 35 v 230; [Link, Politics, Internet] Government Trolls; [Link, Politics] Why identity politics benefits the right more than the left; SSH Forwarding; A Specification For Repeating Events; A Fight for the Soul of Science; [Science, Book, Link] Lost In Math; OpenSuse Leap 15 Network Fixes; Update; [Book] Galileo's Middle Finger; [Bike] Chinese Carbon Rims; [Bike] Servicing Shimano XT Front Hub HB-M8010; [Bike] Aliexpress Cycling Tops; [Computing] Change to ssh handling of multiple identities?; [Bike] Endura Hummvee Lite II; [Computing] Marble Based Logic; [Link, Politics] Sanity Check For Nuclear Launch; [Link, Science] Entropy and Life

© 2006-2017 Andrew Cooke (site) / post authors (content).

Using Choco

From: andrew cooke <andrew@...>

Date: Fri, 30 Mar 2012 23:27:34 -0300

I just finished (before midnight!) a solution to
http://stackoverflow.com/questions/9689436 using Choco
http://www.emn.fr/z-info/choco-solver/

And it's pretty neat.

Previously, I had written a simple depth-first search and a "smart" search
with constraint propagation (along the same lines as
http://norvig.com/sudoku.html).  My DFS was fast when there were few
constraints while my "smart" routine was fast when there were lots of
constraints.  But both were disappointing when not well-matched to the
problem.

In contrast, Choco combines the best of both worlds (although the initial
startup cost is higher).  It's as fast as a simple DFS when it needs to be,
but can also exploit constraints to find quick results when possible.

Which I guess is what you'd expect.

The downside is that it's a big system, and the API docs aren't so great.
There's a manual, which is a good introduction, but when you start to explore
it can become a little opaque.  For example: it turns out that (as far as I
can tell) if you specify a set of values for a variable, they need to be
ordered.  That's not in the API docs, but without it, the system crashes.

Even so, the speed is impressive.

Andrew

PS Choco is Java, but I called it from Clojure.  I really like Clojure - it
seems to hit the sweet spot of functional, untyped and, surprisingly
important, good control over evaluation strategies (lazy and eager).  It's
like a Haskell for dumb people :o)

Choco Update (and New Blog)

From: andrew cooke <andrew@...>

Date: Fri, 6 Apr 2012 20:00:40 -0300

Alas, the comments above were written in haste.  There was a bug (well,
several) in my code.  It turns out that Choco is not a magic bullet - in fact
it performs pretty much the same as my "smart" search.  Which isn't too bad or
surprising, really.

There is much, much more information in the links below, which are to a new
blog I have started with people at work.  I am not "moving" there, but will
use that to document work that involves company time (as this did - although
it also sucked up a lot of my own time, too).

 http://isti.bitbucket.org/2012/04/01/pipes-clojure-choco-1.html
 http://isti.bitbucket.org/2012/04/02/pipes-clojure-choco-2.html
 http://isti.bitbucket.org/2012/04/04/pipes-clojure-choco-3.html
 http://isti.bitbucket.org/2012/04/06/pipes-clojure-choco-4.html
 http://isti.bitbucket.org/2012/04/07/pipes-clojure-choco-5.html

Andrew

Comment on this post