detecting loop in single linked list

Very nice write up about this problem that made me finally understand. The key explanation is finally the fast pointer (hare) will overlap the slower one (tortoise).

The tortoise moves one step, the hare moves two steps. When there's a loop, no matter when/where, for sure they will on the same position. Amazingly, its complexity is only O(n).

coq au curry

Math is always a fascinating subject for me. Particularly the one related to proof and type theory that coined out in curry howard isomorphism. Strange somehow, that I could graduate from bachelor in informatics without knowing this theorem.
My curiousity grows even wilder when I work around people who acquintance with this and using incredible tool such as Coq. It's so cool! Then I dig further into this. Let's see what can I learn from this curiosity.

Is Hawking right?

Following his latest book, Stephen Hawking faces many protests and event condemnation from religious groups. Basically he stated that the universe is created from nothing, not by any trancendental power as religious believe.

In my opinion these religious people are just too reactive. Sometimes it even worst, they challenge Hawking's knowledge with their ignorance and conspiracious statement. This kind of action will only makes people laugh due to its baseless supports and then raises doubtful feeling about religion, particularly among young thinker. This is definitely dangerous!

Therefore I suggest a proporsional and less reactive counter to Hawking's knowledge. A preacher who doesn't even know Newton law in physics, should not give any 'scientific' counter argument. Just revisit the foundation of faith, that there is some trancendental matter that cannot be reasoned.

But, is actually Hawking statement based on solid theory? I don't know, the reporter might be spun, or misinterpreted his intention.

Furthermore does the solid theory violates religious values? I don't think so, though it clearly againsts certain interpretation. For example in the holy Quran, God only said (yes, I'm a devout religious) that human was created from soil or universe were created by Him. There's no further explicit explanation on how it was done. Therefore any theory can emerge in between, including Hawking's one.

How about Hawking's theory? According to other theory there are still loopholes in his theory. Moreover even if it's correct, it won't negate the existence of God.

We should not think of being so important, so God created human in a way such as a child creates a clay statue. Instead it would like process where an engineer creates a CNC machine to shape the raw clay, but God must be better than that. Instead, He created an advanced mechanism to create human by creating the source of the caused of these entire creations. For example, for creating human, God merely creating this universe with its complete rules of interaction among its elements, where at certain point this interaction will create living element and so on and so forth so finally human is created. But the probability is so small! Don't be so naive, do you think just because we think the system is very complex so God cannot ensure a 100 percent accuracy?

What about the universe? I think similarly. Clearly, it is ridiculous to think that that the planets and sun are created in the way we make meat ball or dumpling. Since clearly I'm not smarter than Hawking, instead of proposing my own speculation, I think it is better to use his. The way God created the universe (or multiverse) might coincide with Hawking's theory. But instead of it started from the big-bang, God provided a sufficient condition to make it happened. Definitely He even created an earlier phase of all these thing, e.g. the cause of cause of the caused ... of the cause of the cause of big bang. With His 100 percent accuracy, voila here we are.

Learning math by writing program

A bright idea grab from a talk below. In general he is questioning the mathematics curriculum in this computer age. One suggestion is instead of teaching students to have magnificent skill being computing machinery, it would be better if students are taught to develop that machinery by writing a computer program.

However there is a question left, how we can teach student to have skill for solving basic problems that usually solve without any tool. I feel somehow there are something can be learnt by learning this skillful calculating machinery that might develop our understanding in other field of knowledge.

citation

Nashiruddin Al-Albani. Here is the wiki entry. I shall not give any opinion about his relation to wahabbism or his teaching and judgement on hadits that are considered to be valid for centuries long. I shall only remark his very good and strict understanding of 'sanad' to comprehend Hadits.
He used very strict scientific approach to examine the validity of hadits. Since hadits is not 'provable', its validity depends on the credibility of every person who are listed on citation. Their honesty, ability to remember or even morality are measurements of their credibility.
Al-Albani re-discovered that there are many well known hadits which do not have credible citation path, so these hadits are considered as weak or even fabricated. This finding left a great legacy to give citation on every occasion when a hadits is told, so audiences can examine its correctness by themselves.
The notion of citation also closes the opportunity of miraculous twisted religious teaching. But it opens opportunity of ordinary people who have knowledge to argue with 'holy' people. Using the help of technology, this act is even easier, therefore single interpretation that might be twisted can be avoided. Everybody will be able to contribute and argue logically, regardless their background knowledge. However it may ignite reluctancy to people who think that ordinary people CANNOT interpret religious teaching. Only the ones with broad knowledge are allowed to do that. Agree with that, however when these 'knowledgable holy' people issue a decree that has no valid citation or cannot be inferred from valid citation then this kind of decree should be simply rejected.

Nice Lattice theorem tutorial

http://www.iseclab.org/people/enji/infosys/lattice_tutorial.html

specification pattern

a very nice site about specification patterns to be verified using formal method :

http://patterns.projects.cis.ksu.edu/documentation/patterns.shtml

for computer scientists

http://www.janestreet.com/technology/ocaml.php

Such an explainable stuff during my undergraduate. How could be such programming paradigm get the claws in this respectable area. It's really a great opportunity for computer scientists who cling on scientific field instead of hacking.

It was nine or ten years ago, when I was introduced to LISP and prolog, which that time considered as unprospective programming language, therefore soon they were left and I switched to procedural language; C, pascal and the descendants.

Anyhow I must realize that this is not for mediocre. Meanwhile job market demands more procedural programmer that must be filled.

This post is only encouraging top students to stick to their area of interest instead of devoting theirselves into market demand which is suitable for mediocre like me. Somehow there must be appreciation for hardwork, somewhere!

imagine

Imagine that you are a rich person, e.g richest person in the world. You have a product that is used by many people and many times your product makes these users angry because of the trouble it made. These angry people yelled, and make you a culprit. This accusation haunted your night, that makes you hard to sleep. Once you sleep, it became your nightmare, and left you awake till the dawn.

Since you are a rich person, you find, gather and hire experts to overcome this, of course with very high salary. You hire these experts to prove that your product is flawless, so you'll feel peace since there a proof that you are not the culprit. The experts are working hard, and finally build a tool to prove that, this tool is called SLAM.

graphic equation plotter for linux

We have notoriuous expensive bulky powerful Mathlab for this purpose actually, but we can also use gnuplot.
Here is the screenshot.


Therefore this the online graph drawing will be a history.

what is model checking?

courtesy of Edmund M. Clarke

it's a cool DOF, isn't it?

change!

Long long time ago...

This is the face of semantic web technology, left.













Nowadays it become like this, below right.


It's right that there one thing that constant in this world c h a n g e!
Even in an imminent computer science standardization organization, this change happens. In only four years, the layers are changed!
Imagine if TCP/IP layers are changed! Internet goes doom!


But in my opinion everything went smoothly, the old layer structure is such a guidance or template that ready to refined. I've learnt OWL in the old time, and it become standard now. In that time there were several other that had the same functionality as OWL, but since OWL was developed by W3C, it become standard for current layer.

by the way, it's an interesting artefact.

Drawing function

Function Grapher maybe useful for you who need a simple function drawing application. There are online and standalone application event though it's only for windows.

For me it's a useful tools instead of installing a pirated bulky mathlab.

Math

I realized my problem on this field when I read Knuth's TAO Computer Programming. I needed 3 months just for understanding chapter 1.1. and unable to solve even one problem. Instead of solving the problem I can only proved the answer which is provided. And now I must live with it. Such a monstrous alien living beneath my skin. Soccoro!!
A couple year life in procedural mechanism, made my math skill undeveloped even decreased. Some contacts have been established to be my tutor. Thanks God.


Recently I found some famous Linux terms that was derived from mathemathical terms. Linux engineer must be also good mathematician. init-bottom which is appeared on the beginning of linux booting process is depicting the lower partial ordered set on lattice of set theorem. So does top, which is a command to monitoring all task that currently runs, it is the highest partial ordered set on a lattice. This init-bottom and top depict such a complete lattice. Whohoho, almost a decade living with it, I just notice it now. Poor computer science student!

Finite of An Infinite

Topik "kuliah" berat hari ini.

Definisi infinite adalah suatu hal dimana selalu bisa dibuat kondisi yg lebih besar/kecil, pokoknya ada kelanjutannya lah (susah). Daripada suatu hal yang tertentu yang bisa dinyatakan dengan nyata, ke-infinite-an lebih cocok jika dinyatakan dengan fungsi.

Misal ada tak berhingga bilangan bulat, buat aja fungsi f(x)=x+1. Untuk bilangan real, buat aja fungsi f(x)=x/2. Operasi fungsi-fungsi itu selalu bisa dilakukan dalam domainnya berapapun angkanya, sehingga terbentuk deret bilangan infinite.

Nah ide "kuliah" hari ini ternyata ada orang yg menggunakan ke-infinite-an ini untuk merumuskan konsep Ketuhanan. hehehhee. Ada-ada aja. Kalau tidak siap membaca dengan hati-hati sebaiknya tutup browser web anda.

Perhatikan sequence berikut [terurut dari akibat ke sebab]:
daun jatuh, angin bertiup, tekanan udara, panas, matahari, fusi, ... infinite.

konsep infinite adalah open-conclusion, selalu bisa dicarikan keadaan yg lebih... demikian juga dengan sequence diatas.. selalu bisa dicarikan penyebab untuk sebuah akibat... Ini bahaya karena bakal ada penyebab adanya Tuhan.

tapi ada masalah besar dengan konsep infinity ini, jika dikaitkan dengan sebab akibat. Sebuah
kejadian yang terjadi akibat kejadian lain tidak mungkin terjadi jika kejadian penyebabnya belum selesai. Berkaitan dengan konsep infinity yg tidak berbatas, terdapat kontradiksi dengan sebab akibat ini. Tidak mungkin suatu kejadian selesai kalau penyebabnya belum selesai. Hal ini membawa keraguan atas konsep infinity, this infinity must be finite, agar memenuhi sebab akibat tadi. Finite ke mana?