Forrest Sheng Bao's Cyberhome

Choice rule not choosing

forrest — Sat, 14 Apr 2012 14:35:48 +0000

The two answer set programming (ASP) programs below are different.

Program 1

1{a(D):b(D)}1.

b(x).
b(y).

Program 2

1{a(D)}1 :- b(D).


b(x).
b(y).

To understand their differences, see their answer sets respectively.

Answer set(s) for program 1

Answer: 1
b(x) b(y) a(y) 
Answer: 2
b(x) b(y) a(x)

Answer set(s) for program 2

Answer: 1
b(x) b(y) a(y) a(x)

Now I think you have figured out. The condition in choice rule plays a role.

Why knowledge representation matters

forrest — Tue, 03 Apr 2012 03:05:37 +0000

Knowledge representation (KR) is a branch of AI, but not at hot/popular/attractive to young AI researchers as other fields, such as machine learning (ML).

However, it matters. (I will explain later in this post why it is not as popular as machine learning.)

Allow me to use one example. I am writing an email to Dr. H. I usually write to Dr. H while CC'ing to Dr. X on issues about research topic A. But today, I do not CC to Dr. X but Dr. Z because today's email is about research topic B.

Gmail, maybe using some statistic strategy, thinks I put Dr. Z by mistake and suggests me to put Dr. X in the CC field.

SSH log-in without password

forrest — Tue, 07 Feb 2012 05:49:46 +0000

This page has been moved to http://forrestbao.blogspot.com/2012/02/logging-vis-ssh-without-password....

Trimming suffix or perfix of a string in Shell

forrest — Thu, 05 Jan 2012 09:15:18 +0000

Post moved to

http://forrestbao.blogspot.com/2012/01/trimming-suffix-or-perfix-of-stri...

Adding two SCALARS in POINTDATA for one vtkPolyData object in VTK

forrest — Wed, 04 Jan 2012 06:35:30 +0000

by Forrest Sheng Bao http://fsbao.net

In VTK (either the file format or the library), we sometimes associate more than one scalars to points. I just figured out how to do this in VTK (in C++, similarly in its Python, Tcl or Java wrapper).

Suppose I have a vtkPolyData pointer

vtkPolyData* mesh;

and two vtkDoubleArray (you can consider a vtkDoubleArray as a list of scalars) pointers

vtkDoubleArray* depth; 
 vtkDoubleArray* curv;

This is how I do it:

depth->SetName("Depth");
mesh->GetPointData()->SetScalars(depth);
curv->SetName("Curvature");
mesh->GetPointData()->AddArray(curv);

You may test this by writing mesh into a VTK-format file:

vtkPolyDataWriter* writer=vtkPolyDataWriter::New();

Fixing Firefox plug-in container problem by forcing it to crash

forrest — Fri, 30 Dec 2011 03:14:33 +0000

by Forrest Sheng Bao http://fsbao.net

I use two important plug-ins in Firefox, Adobe PDF reader and Flash player. But they sometimes do not work after having been used in Firefox for a while. The embedded PDF reader gives you a black blank after you open several tabs of PDF files. The embedded Flash player just doesn't play movies after a while. Restarting Firefox doesn't always work.

I just found out a solution - killing the Firefox plug-in container to force it to reload. First (optional, for advanced users), find out the plug-in container.

$ ps -A | grep plugin
29981 ?        00:00:07 plugin-containe
30024 ?        00:00:00 plugin-containe

The RIGHT code to enable MathJax on your website

forrest — Mon, 26 Dec 2011 01:23:30 +0000

by Forrest Sheng Bao http://fsbao.net

I started using MathJax to display math on my blog (Drupal and Google Blogger) recently. OMG, my life is much easier. LaTeX is easier to type math than MathML and MathJax does not render math into pictures but vector symbols.

But I noticed two problems.

Firefox for Linux has a little problem with the Javascript code on MathJax official instruction. The fonts are odd - no such problem on Chrome for Linux.
MathJax's official instruction does not work for Blogger's HTML template.

Then I found out this instruction that fixed both of my problems:

Happening sequence for plans with both simple and durative actions in PDDL2.1

forrest — Sun, 18 Dec 2011 10:47:18 +0000

by Forrest Sheng Bao http://fsbao.net

I have been struggling with a definition in an important paper about temporal planning in past few weeks. And today i finally understand it with the help of one of the authors. In his words, this definition is sorta counter-intuitive. So I am now writing this blog and hope it will help others struggling with this as well.

Accessing matrix elements of different indexes in different rows in Octave or MATLAB

forrest — Sat, 17 Dec 2011 12:27:50 +0000

Here is a tricky programming problem in Octave or MATLAB. Given a matrix A, and another array Y, how to build a new array Z such that

Z(i)=A(i, Y(i))

Adding model library in Cadence spectre2

forrest — Fri, 16 Dec 2011 23:44:54 +0000

To selecting device simulation model in Cadence Spectre for Cadence Affirma, here is how.