Alberto Alonso Ruibal's Blog

Chess engine development is one of the most brain-crushing activities I’ve been involved on the last years. Last nigths I was working again on my Carballo Chess Engine with some advances.

First of all I decided to leave Negamax and go with Principal Variation Search (PVS). Also decided to implement separate methods for root nodes, PV nodes and null window searches. On previous experiments PVS was performing worse than Negamax, but I discovered the reason: the aspiration window has some implementation issues with PVS: when the search for a move fails low at the root node the move must be researched enlarging the window.

I was very stranged of why Futiliy Pruning was not working for me, but finally discovered the reason: a simple sign change after evaluation was the reason! Also implemented to store the evaluation values on the Transposition Table (TT).

The next step: why Carballo searched much less depths than other engines, it was due to quiescence search. I was generating checks for the first 4 PLY’s of quiescence, but some other engines not, so this was the reason. I decide to generate only checks on the first PLY of quiescence and only for PV nodes. Also modified a bit the move generation to optimize for quiescence.

During this time also found many interesting bugs, I was storing on the TT the bound and not the score when failing high/low, also on PV nodes is better to use only the TT for ordering and not to return scores from it, this helps avoiding draws. Also found a serious bugs involving time management (was taking as reference opponent’s time) and with contempt factor on IID searches corrupting TT entries. Finally added a Pawn Push Extension and removed the Recapture Extension and now some extensions now depend of the node type.

Running some test tournaments, I hope to get some good results soon and add the improved engine to my Mobialia Chess.

Jim Ablett has published a packaged executable for my Carballo chess engine. He also made a pretty logo for it, shown here. Check his page to download executables for Carballo and a lot of other chess engines: Jim Ablett’s Winboard Chess Page. Thanks Jim for your great work!

Mañá vou facer unha presentación de Android e organizar un pequeno workshop na SobrosoParty (http://www.sobrosoparty.es). Tamén falarei do meu novo proxecto Mobialia e das aplicacións para Android que teño feitas. A presentación de mañá se pode descargar no seguinte enlace:

• android_sobrosoparty.pdf

Lukas Laag has written me about his new  GUI for the Carballo Chess Engine  using the Google Web Toolkit (GWT) and his SVG Graphics Library for GWT, libgwtsvg.

GWT is provided from Google to develop applications in Javascript programming in Java. It conterts the Java code to Javascript, and the application is run on the browser, without any additional plugin.

This interface is quite better than the sample Applet from Carballo, it has move history, legal move hightlighting, and SVN graphics. It can be used from:

http://www.vectomatic.org/gwt/libgwtsvg-chess/libgwtsvg-chess.html

He also wrote an article explaining the difficulties of his project. Thanks Lukas for your work.

Recently, navigating the Debian repositories I found Rakarrack, an Open Source Linux program to simulate various guitar effects in real time. This sound effects are often done with expensive physical sound processors, but this application makes it all with only one cheap computer (well, I suppose that the quality will rely a lot on the sound card).

Each effect is a module and and has its owns parameters which can be adjusted with sliders from the GUI. Multiple effects can be chained in different configurations.

For the audio input and output, It uses the Jack Sound Server. Initially Jacks is a bit complicated to set up but is very versatile. I use the qjackctl to configure and run Jacks simplifying this task. First we start qjackctl and from its GUI, start the jack server. Then run Rakarrack, and with qjackctl we connect Rakarrak to the system sound output and input:

The latency (the sound delay) of Rakarrak is quite good, but depends a lof of the Jack server configuration. This snapshot is the configuration that I am using from qjackctl: the Latency is the important value, and can be minimized adjusting the “frames by period” parameter:

I played a lot using different presets (it has lots of pre-configured) and there are some quite good, but others does not sound as good as a physical pedal, maybe also by le low quality of my notebook sound card.

It also has an integrated guitar tuner, but for this purpose I prefer Lingot from my Friend Iban Cereijo.

A lot of years ago I tested Guitar Rig, a quite pretty (and expensive!) windows applicattion for the same purpose, but then the latency of the sound was too high. Rakkarrak is simpler but enough for most non-professional guitar players, and I like it a lot!

http://rakarrack.sourceforge.net/

Na úlima Noite Galega das Telecomunicacións (a cena anual do colexio de enxeñeiros de telecomunicación) tiven a sorte de coñecer a Xosé María Fernández Pazos, director da Revista Codigo Cero e do programa da Radio Galega Banda Ancha. Por certo, a última hora, a directiva do colexio tomou a esperpéntica decisión de non reparti-los exemplares do número especial da revista “Código Cero” editados para a Noite Galega, supoño que é unha cacicada de Televés, que ten copada a xunta directiva, xa que na portada da revista aparecía propaganda de BluSens e de Arteixo Telecom.

Son de agradecer estas iniciativas nuha terra na que a radio e a televisión públicas están inundadas de vacas e mariscadores, un auténtico oasis no deserto. Todo o meu apoio para eles:

Blog do Programa Banda Ancha

Using mencoder in Linux, we can convert any video to FLV and embed it in a web page with Flowplayer. In this sample video is encoded at 320×240 300 kbps and audio at 56kbps:

# mencoder -forceidx -of lavf -oac mp3lame -lameopts abr:br=56 -srate 22050 -ovc lavc -lavcopts vcodec=flv:vbitrate=300:mbd=2:mv0:trell:v4mv:cbp:last_pred=3 -vf scale=320:240 -o out.flv in.avi

Try to find the "R"

When you travel, you are allways afraid that someone can steal you the few things that you carry, but what you dont expect is that who tries to steal you was the council of a city like San Sebastian.

Last week we travel to Basque Country and in San Sebastian we parked at a zone painted with white lines. When we returned to the car, we found that we were fined by the local police. I was annoyed and went to speak with the policeman who fined us.

He told me that the parking zone was only for residents, and that was painted with an “R”.

- Me: I cannot see this “R” ¿where is it?

- Policeman: Well, I already said that must be repainted

- Me: then, why did you fined me?

- Policeman: My boss ask me to fine everyone non-resident who parks here because there is a traffic sign there saying this zone is only for residents.

- Me: ¿There? ¿Where is the sign?

- Policeman: There (pointing 50 meters away)

The sign was smaller than normal traffic signs and behind other sign which was hidding it. In other cities resident zones are painted in Green or in Red, but in San Sebastian the council prefers to earn more money confusing their visitors.

En cuanto a las distribuciones de Linux siempre he sido un talibán de Debian, pero hay aplicaciones propietarias que requieren de ciertas distribuciones de Linux para poderse instalar sin problemas, y casi siempre suelen ser compatibles con Red Hat Enterprise Linux (RHEL).

Pues bien, para estos casos tenemos CentOS, que es una distribución de Linux totalmente compatible con RHEL. Sigue las mismas versiones que Red Hat, así una Centos 4.7 es como una RHEL 4.7 y los paquetes son los mismos, idénticos en versiones, y además tenemos actualizaciones gratis de por vida (para Red Hat hay que pagar la subscripción a Red Hat Network). También es muy fácil habiendo instalado un RedHat poner los repositorios de CentOS y convertirlo a un CentOS.

Como es de suponer, CentOS tiene muchos de los defectos de RHEL, como que para actualizar de la versión 4 a la 5 te recomiendan reinstalar desde cero. Yo administré servidores Debian en los que durante muchos años siempre estábamos en la última versión estable sin tener nunca que reinstalar… No obstante se añaden algunas mejoras en unos repositorios separados (CentOS Plus), que permiten por ejemplo tener los PHP 5 en una RHEL 4.x, cuando los repositorios “oficiales” de Red Hat proporcionan sólo PHP 4.

Y por supuesto que, añorando mis Debian, me he instalado el apt para RPM’s, que es una herramienta mucho mejor que el up2date o el yum.

Tras años de embarque, ya tengo un cascarón vacío (léase casa) para llenar de muebles… uff, ¿pero qué le ha pasado a mi cuenta bancaria? Ah si, que llevo pagando que si hipoteca, que si notarios, que si albañiles… pero entonces ahí está Ikea, el Burguer King de la decoración, donde por cuatro duros (bueno, ahora son euros) te puedes comprar unos muebles estupendos… bueno, de apariencia estupenda, aunque habrá que ver cómo salen a la larga.

Para los geek como nosotros , que no somos capaces de pensar sin un ordenador delante, Ikea tiene un programa que te permite amueblar virtualmente tu casa. Comenzó como Ikea Kitchen Planner pero ahora es el Ikea Home Planner, ya que incluye también tiene muebles de salón y dormitorio, y por supuesto es gratis y te lo bajas desde la página de Ikea.

El programa en sí es cutrillo, sólo te deja amueblar un habitación a la vez, los techos son siempre planos y a la misma altura, los renderizados son muy básicos,  y no te deja dibujar nada más que puertas ventanas y “cosas que puedas comprar en Ikea”. En contrapartida es muy, muy fácil de usar, quizás el que más de todos los que conozco. Aun así, tiene detalles muy buenos, como por ejemplo el poder planificar el interior de los cajones de la cocina, siempre con accesorios de ellos, claro. Y lo mejor de todo es, que una vez dibujados todos los muebles, te saca una receta con precios (siempre baratos, claro) para que te lleves a tu tienda Ikea.

En fin si tienes poco dinero, esta es la tuya, si papi te paga los muebles mejor vete a una tienda de toda la vida, que los muebles de Ikea tienes que montártelos tu, y aunque las instrucciones vienen todas con dibujitos y no hace falta saber leer, a lo mejor se te puede romper una uña al coger el destornillador…