#PRAGMA29 Student Presentation Award Winners

Congratulations to all winners of awards from the 29th Pacific Rim Application and Grid Middleware Assembly Student Presentations Session!

  • Best Technical Talk: Hiroki Ohtsuji . Breaking the Trade-off between Performance and Reliability in Network Storage System
  • Most Innovative Talk: Soetrisno Cahya . Adjacency Hyperedges Matrix, A Hypergraph Model for Constructing Composite Object Relationship
  • Most Impactful Talk: Takuya Yamada . Proposal of indoor evacuation system with smartphones
  • Honorable Mention: Denny Hermawan . Design and Analysis GPU Computing for Molecular Dynamics Simulations with AMBER Applications
  • Honorable Mention: Irfan Fadhila . Performance Analysis of Virtual Machine and Container for Cloud Based High Performance Computing Platform

PRAGMA29, or the 29th Pacific Rim Applications and Grid Middleware Assembly, is an international workshop pursuing large-scale networking technology, data science, big data, and solving the problems that matter, among other purposes. The Student Presentations Session were arranged based on a lightning talk concept, where each presenter is allowed only five minutes to present his or her work, and only one common presentation medium (slides) is permitted.

The three awards are considered to be equal in terms of prestige. The two honorable mentions are added for this workshop due to very close results. The full list is after the break.

NOTE: This is an unofficial release text. Do not consider this a reliable or official source of information for PRAGMA or its affiliates. While the author does work for PRAGMA Students Steering Committee, he does not represent it in publication of this text.


Continue reading #PRAGMA29 Student Presentation Award Winners

How to Organize an Event: Lessons from #PRAGMA28

This post was started from the time that PRAGMA28 was held in Nara.

By helping out at the 28th Pacific Rim Applications and Grid Middleware Assembly I picked up a few pointers on how to run a good (successful or not) public event. #PRAGMA28

Universal Access & Facilities

Event organizers need to cater to differing needs of various people. Make sure that all registered guests’ needs are met. This includes but not limited to:

  • Religious needs: For Muslims, providing just Halal food is bare minimum. Prayer area, if possible, should be prepared. Access to cleaning basin, silence, and clean floors will be appreciated. If in doubt, having a Muslim contact in the organizing team is a good idea. Do note that vegetarian food may not be Halal. One drop of alcohol is enough to make it unsuitable for Muslims.

  • Accessibility: Most places in Japan are already blindness and wheelchair-friendly. If a guest needs to bring service dogs, make sure they are allowed or have places to wait at.

  • Followers’ entertainment: Maintain a list of attractions or activities that accompanying non-attendees can use or enjoy while outside the conference halls.

The more you do to accommodate attendees, the better.

Publishing & Printing stuff

  • Repeatable Publishing: Use mail merge for everything that’s gonna get repeated. Certificates of participation may be requested on-the-fly for people who really need it (when name-tag is not enough to prove participation)

  • In student-focused conferences and events, always have a certificate of participation template handy. Some schools require them to record participation of the students, and use them to improve their annual reports.

  • How to emphasize names on a name tag or address someone:

    • Chinese names must be put on a single line, even if written using alphabet. I’m not really sure how to address them, though.
    • Japanese names are emphasized on last names (except in really international or informal events). Japanese names are usually written in Lastname Firstname format (and not “Lastname, Firstname” even in formal cases). This can lead to a lot of confusion. Some Japanese people write their names as LASTNAME Firstname or Firstname LASTNAME, so use this as a guide.
    • Westerner names should be emphasized by first names, except formally. I think this is a basic case, actually.
    • Thai people have nicknames and it’s okay to use that, except formally. Professional or military titles (Prof., Dr., Col., etc.) can be used together with nicknames. In Thailand, Dr. is more associated with Ph.D. not MD.
    • New from PRAGMA29: Indonesians can legally have just one name or take a parent’s name as last name. It does not indicate how great a person is. If a name has “oe”, read it as a “u”. For example, Soekarno = Sukarno. Sukarno uses “u” in his own name, but the airport named after him is written as Soekarno-Hatta. (Hatta was his vice president.)
    • As an exception to any and all above, if somebody introduced themselves with a specific name, use that name to address them. Get dynamic about name emphasis. Keep those IF clauses handy in your Excel file so you can modify the mail merge quickly without affecting the original data. Also, I think it would be even better if we can let attendees “design” their own name tags. Give them two lines and display result on the fly in the registration process.
  • Always write event name and date (optional: location) on the name tag. Sometimes it can be used as proof of attendance for accounting purposes. It’s also a good memorabilia.

  • According to a recent tragedy where a certain Christopher’s name tag at GDC (?) was taken by the secretary office for accounting purposes, I think it could be a good idea to print out an extra card as “proof of attendance” for each participant. These could be just business card-sized and shoved into the name tag package.

  • According to Matt Cutts, to prevent the badge flipping around problem you can just print it both sides. Also mitigates damage from rain that does seep into the badge pocket. Alternatively, consider a two-hole mount for badges.

  • Give out breakaway lanyards. Some people (this is from a non-PRAGMA case) do complain that the non-breakaway lanyards are unsafe. While the chance of death by strangulation in an academic conference is low, I think it’s a simple sign of thoughtfulness. If it’s expensive, just inform the participants that they can return the lanyard somewhere or have a box with “LANYARD RETURN” printed in boldface.

Things you need

  • A proper business card case IS NECESSARY. Even if you are a student and not permitted to use school printers to print your own card and too damn broke poor to pay to get them printed outside (means: you should actually have a few cards as an organizer!), at least have an empty case in case a senior attendee gives you one.

  • Prepare spare awards and gifts. Ties can and do happen, or suddenly more people need recognition for something.

  • Always have USB cables and drives handy. DisplayPort adapters (those white little expensive Mac dongle bastards) too. Somebody will eventually need it. For expensive stuff, mark with your institution name.

  • Always keep Internet access available. Sometimes it’s necessary to check emails, revise slides, send print jobs to the print servers, and other things. Consult with the venue early and test the network under a large number of users. Prepare a backup access. Maybe you don’t need it, but someone will, especially if it’s an international event where foreigners without data plans join.

  • Have some spare power strips. You need ten for that room? Get one or two more if possible. They do break down under stress.

  • Document everything. All posters, all speeches, all slides. Gotta collect them all. Videos would be even better. This also gives everyone importance.

Your first semester in university doesn’t have to be miserable!

Learn how to Learn and make your first semester in a new school a much, much better experience!

Clueless freshmen, gather round!

Well, let’s just say that by getting into a university you have undertaken an important leap into a new land. The land of academia, the land of self-study, the land of distractions, the land of unforgiving exams without partial credits, and probably a hundred things that could be happening at the same time. By stepping into a campus, you have put a lot of things into motion. All of those do not matter: right now you are a clueless freshman, young and fresh, yet at an extreme risk of being misguided and misinformed.

I’ll just tell you a few tips here in small, manageable chunks. They will mostly deal with engineering, maths, and computers though because that’s what I’m specialized at. The focus is mostly on Thai schools, because that’s where I came from. However, I hope it is also applicable to other countries as well.

Rule 0: Scout and pick your battles.

Victorious warriors win first and then go to war, while defeated warriors go to war first and then seek to win. — Sun Tzu

The entire campus is a battlefield, and each class can be a really tough beast! You must know which battles you can fight and how many fronts you can take at once. There are small skirmishes like your in-department elective classes which are obviously your specialization, then there are great battlefields in which millions of great soldiers were slain. Those classes are faculty-level lectures like Chemistry or General Physics.

Learn to scout your battles beforehand so you can pick your battles. You need to know:

  • Your curriculum: how many credits you need, which classes are required, and which classes are elective.
  • Who’s teaching which class.
  • The time of week and how much free time to have.

Taking too many classes, especially during the first semester when many “basic” classes such as calculus and chemistry can be an overkill, can burn you out quickly. Sometimes curriculum comes with a class plan, a by-semester plan that tells you which classes you should take which semester. Sometimes this is really helpful, sometimes not. Use your judgement and adjust accordingly.

If you talk to your upperclassmen, you will learn that not all lecturers are the same . Even if they are all teaching the same class, they might have different styles, experience, or level quality. Some do not give a damn about your education, while some go out of their ways to answer absolutely everything as long as you have time to listen to them. Less experienced lecturers (especially those without “something-Prof” in their names) can be very enthusiastic and understanding of your concerns, but may have a hard time coming up with an answer for a complex question. Some lecturers have a mindset that you must bring something to the table to talk to them. This means you can’t just come in and ask. You must have prior information, such as a list of theorems that you want to use, references, and most importantly your attempt at the work. Therefore, if you have a choice, choose your lecturers wisely.

As long as you follow the curriculum and do not pick any classes you are barred from (e.g. “Engineering students must take Engineering Mathematics and not Calculus”). No one, not even your adviser, has any absolute say over which classes you pick. You might get liked or get hated, but you won’t get expelled for picking a class.

First Day: Syllabus, the map of the class.

Syllabus is the metadata of the class. Everything important is written there, including lecturer’s contact information, when you can meet him/her (called office hours ), list of teaching assistants (TAs), hours, what will be taught each week, how will you be graded (typically 100% exams, or maybe 80% exams and 20% reports, but it may vary between each class).

This information is extremely important. Sometimes, a teacher may actually write what will be on the exams right on the syllabus. Sometimes this can be slightly less or more than what is lectured in class.

The syllabus is the most important document in the class. Normally you would get one in the first class, but if you don’t for any reason, you must contact the lecturer, or one of the TAs, or consult the website, as soon as possible to obtain one.

First Week: Learn early, study regularly, and do your homework.

The last thing I want to see you do is cramming everything 24 hours before the exam and go to the exam hall tired. That will be your bad end in the class. Instead, think of learning as laying a brick wall. You want to allow each layer of bricks to set into place before you start with the next layer. If you do it too quickly, you will do poorly and the bricks will collapse, giving you a messy wall that nobody wants. Learning slowly but regularly allows your brain to retain the information for much longer than cramming everything in a few hours. Instead of reading everything right before the exams, try reviewing (using both reading, writing, and recall, which I will explain later) every week or every few days.

Do not leave your homework unattended. (Good) Homework assignments are designed to improve and test your understanding of the content and is a way to make sure that everything goes in a regular pace. Some good teachers also give well-detailed homework feedback that points out where you went wrong. Being wrong can be very helpful in your learning process.

Second Week: Learn your limits and learn to chunk.

By the second week of the class you should have gone beyond the “introduction” phase. This is when the teacher actually opens chapter one in his lectures and begin firing more advanced content at you. It may feel overwhelming to learn large concepts such as complex equations and four-character Japanese word, where each character has like 20 strokes. That’s absolutely normal. It’s how your brain works.

Your brain is wired to receive only a few things at a time, but have a very powerful back-storage or long-term memory. Average humans cannot hold more than three or four things at a time in their brains, but this “thing” is a very extensible concept: it can be a single number, a single Chinese character, or a whole parallel parking process. The brain uses what we call “chunking” to expand small facts and steps into larger concepts and algorithms.

In this chunking process, your brain groups many things together. Instead of writing each stroke, your brain can learn that the strokes go together to form a character, and many characters form a word. Training and repeating your chunks will make it stronger, and that’s why teachers insist that you say those words in class out loud, or solve a problem on a blackboard on your own — solving various problems allow your brain to form a better chunk of the kind of the problem, allowing you to do it better and quicker. It is especially important to exercise your mind a little by solving problems from scratch.


Relaxing is as important as, and at times more important than, studying.

Have you ever wondered why you study so well when at your desk, but figure something out while in the shower? That’s because your brain has two distinct modes: focused and diffused. Focused mode is used when your brain wants to do something very deliberate, like solving mathematical problems or learning to write a new word. It can help you learn new concepts and create chunks. This is common knowledge. However, where your hidden power lies in is the diffuse mode. While your brain is in diffuse mode, it can synthesize and map multiple chunks together. This allows you to create powerful solutions to the problems to have. And what’s best about the diffuse mode? It runs in the background while you relax!

Switching around between the focused and diffuse modes can be beneficial to your study. There are many techniques that help you do this. One of them is Pomodoro. Essentially you must dedicate 25 minutes to work, then a mandatory 5 minutes of rest. Both are necessary, as working too much will tire you out and not allow the diffuse mode to kick in.

When faced with great difficulty, back off. You will synthesize a solution better when you are relaxed because your diffuse mode has a very fast solution-finding speed compared to grinding your mind or bashing your head on it. This principle also applies in exam, which I will explain later in its own section.

Dealing with procrastination and the torture of study sessions

Like how water flows down to the lowest point, your mind will also seek to do whatever it feels relaxing. Work is tiring. Studying is a torture. I know.

I would break a very big study goal into manageable sessions. Instead of saying I’ll do 100 problems this month, I’d just do 5 problems a day. I will still have 10 more days for slack. That sounds like a good deal, the “only $0.15 a day” (for 10 years) kind of deal. Instead of saying I’ll finish this report this week, I’d break it down into five sections, each to be done each day of the week. Breaking things down and focusing on doing it (the process ) and not completing it (the product ) will make it easier for your mind to get on it, as individual steps and the simple act of “just working” is not as steep as “finish this whole thing.”

Now write that goal onto a planner or something you will look again in the morning. Writing things down is like a save function for your mind. Free up your working memory by putting it onto some other medium that’s not your head. That way you can concentrate on getting it done … pardon me, doing it , tomorrow. When tomorrow comes, eat your frogs first and do the biggest, hardest, or the most daunting task first. Your fresh mind that was just fully fueled by breakfast (important!) and sleep (also important!) can tackle hard subjects better than the exhausted mind in the late afternoon.

Finally, don’t forget to reward yourself. Your brain likes rewards and has a dedicated part for this function. Every time you do something good, reward yourself a little. Your little zombie in your brain will appreciate it.

Testing yourself is better than reading over and over.

Simply rereading (or merely highlighting) worked solutions and text may seem like a lot of progress because hey, I just read the whole thing again! But guess what: it doesn’t work the way you think. Reading, listening, and maybe watching videos only let you passively sense the material using your eyes and ears. Sure, some of it might go into your brain, but the best way to retain everything in your brain is to test yourself. Close that book, try to recall as much as possible from your head. Write the outline for the whole chapter and as many points as possible on a sheet of paper. This act of “active learning” forces your mind to write the material over and over, strengthening the memory in your head.

A similar kind of “illusion” occurs when you highlight text. Hilighting text gives an illusion that you’re making a lot of progress, but it is not a good idea to highlight too much. A better way to annotate your book is to use a pencil to write in the margins or on a post-it. Summarize the whole paragraph or make a simple derivation from the text yourself. Then test yourself about it.

If you want to learn more, maybe you could google for “Learning Pyramid theory.” So far it works for me.

Teach to learn.

If you want to go fast, go alone. If you want to go far, go together. — African proverb

While testing yourself is better than reading, testing your friends and getting tested by them and actually discussing the problem is much better than testing yourself on your own!

Despite how competitive it may be (for example, classes with a “grade on a curve” or “limited A” policy), you need friends to succeed. As I told you earlier, passive learning is not a good idea. A better idea is to teach your friends by writing up your own version of the textbook, take turns giving lectures to your friends, test each other, or becoming a “master” of a specific course and help your classmates in a group. Teaching means you must recall everything from your brain, derive the formulas live, and demonstrate mock labs live. Extensive “my lecture notes” teaching material must also be well-prepared. Everything that leads up to teaching will force you to learn, and will make you keep more content and skill in your mind. Discussing with friends also open you to other perspectives of the same thing. Maybe the way your friend is deriving all those equations is much better than yours and you should learn from them, but your substitution rule just rocks and they can learn from you. When two great minds meet, many good things can happen, so talk to your friends!

Note, however, that you have to be punctual and disciplined when doing group work. Do not let it (d)evolve into a pizza party before the study session ends.

Change your place.

Your mind inadvertently associates a place you are in with some pieces of memories. This is not desirable, as you will have difficulty recalling this information later in the exam room, which is not your favorite room. Go out of your comfort zone and read in many places so the place-content association is weakened. Generally, during exam week, campus libraries may have extended or 24-hour service.

Note that using McDonald’s or public locations with high patron turnover is frowned upon. If you really need to use this kind of public space, remember to order food and service proportionately.

The Exam

The week leading up to an exam, you should have already learned all material well by using techniques above. Get at least 8 hours sleep every night no matter what, as sleeping clears up your mind and the sleeping mind is fully relaxed, free of stressing thoughts. Do not skip a meal, especially on the exam day itself. Stop all heavy study activities 24 hours before the exam. Maybe you will want to freshen your mind a bit by doing a few problems, but that’s all you should do. Do not reread the whole book and retest yourself on it the day before exam.

If a cheat sheet (i.e. your personal reference or note) is allowed in the exam, make your own from understanding. Remember chunking and recall? Synthesizing and writing those concepts down yourself will give you a clearer imprint of the data in your brain, allowing you to utilize it better. Most of the time “one A4 cheat sheet” is just a ploy to get you to read and write.

It may be wise to have an emergency alarm clock: your family or friend to call you to exam using the phone. If you live with someone, ask him/her to wake you up, violently if necessary. Prepare or find at least 2 or 3 means of transportation to your campus.

If your university has a dress code (almost all Thai universities have prescribed uniforms), follow it. Prepare at least two non-mechanical pencils, two pens, and a plastic eraser. Prepare at least your student ID and another government-issued ID. Arrive at least 1 hour early to your campus, and at least 15 minutes early at the exam room. If you suspect that the venue may be changed, contact the faculty hosting the examination immediately. If you cannot find your credentials, go to your registrar office the first thing (as early as possible) and ask for a temporary certificate of identity. Your campus may have different procedures, but this is what I got.

While you wait, meditate. Close your eyes, think of nothing. Let every sound flow through your ears. Let air flow through your nose. Let everything in the universe flow through as you were not there. Feel your breathe. Do this for at least a minute. You will automatically relax and enter diffuse mode soon enough.

When you are called to the exam, sit down, check all pages, write your name if it’s okay. Now, onto the real tips. Skim the whole test and pick the hardest questions first, BUT only do it for less than a minute or two. When you are stuck on it, meditate a bit and move on to an easier question. While you struggle with the hard questions using your focused mode, when you meditate and switch to an easier question, your diffuse mode will kick in and will contemplate on the answer on its own. Use your brain power on the easier questions first. When you are stuck, rotate again. Be extremely thorough in your answers and write as much as possible.

You should also write your understanding or interpretation of the question if it seems unclear and the examiner/proctor does not give you an answer or clarification. Some teachers automatically give you the benefit of doubt if you tell him/her how you interpret the question. It also helps you get on track with the question. Show all your work, then summarize your answer again at the bottom. Circle or underline the answer if asked to do so.

When you are done, check everything again and make sure it is in order. If you are allowed to leave the examination room early, do it. When you are out of the room for any reason, leave the premises immediately and do not talk to anyone. You have used your brain enough the last hour — no need to waste it more.

If you have any problems with a class:

  • Ask a TA or the lecturer. Do not guess. Do not speculate. Do not trust anyone who claims to have authoritative information until it can be proven. Sometimes a series of speculations become an unofficial fact, which is not true at all.
  • Always show that you have already tried before you ask.
  • Your problem with a class is your problem that should be addressed directly by a teaching staff. Use your judgement whether or not should you involve your classmates. An absolute NO is whenever it is related to grading, exam, late days, and anything that directly affects your score.

PSA: You are free to choose your kind of fun!

There are many kinds of fun in universities! This is a great chance to meet someone new! However, not all activities and student assemblies are totally honest about the presentation or interpretation of their activities.

Every year, many freshmen in Thailand are rounded up and brought to what they call “SOTUS” activities, misinformed that it is a mandatory activity. “Cheer class.” “Pep.” “Icebreaking.” “Bonding.” Those words are just disguises for what actually can amount to systemic collegiate hazing. Good, diligent students have lost their lives from this “tradition” of extremism and violence. Being a “senior” does not imply any actual seniority.

Please contact your adviser or a trusted upperclassman if you feel uncomfortable or being abused! You have all the rights to walk away from any campus hazing, even if it is disguised as a mandatory icebreaking activity. You can also contact me (the email should be in About section of this website) or any social volunteer anytime. I am neither press nor counselor, but I am not your enemy and I am willing to hear you out. (Please be descriptive in your email subject.)

References & Disclosure

This article was written as a final project for Prof. Barbara Oakley’s Learning How to Learn: Powerful mental tools to help you master tough subjects , a Massive Open Online Course (MOOC) from University of California, San Diego (UCSD), available at no cost at Coursera. Most of the content in this article, especially those regarding memory, learning techniques, and anything directly related to your brain, is derived from this subject.

That said , some of the content here was added from my own experience as a student. I was a student before, and I hope my experience, along with Prof. Oakley’s wisdom, will help you learn better. Now go to school and do your best.

[Math] How to find drop rate after killing “x” monsters

English version available after the break. Summary: we are talking about how to find out the number of monster kills necessary to get a number of drops using statistics.

อีกประโยชน์ของวิชา prob stat: คำนวณว่าต้องตีมอนกี่ตัวถึงจะมีโอกาสเก็บ rare drop ได้ครบ โดยใช้ negative binomial distribution (Pascal distribution?)

สิ่งที่เราอยากรู้คือ CDF (cumulative distribution function) ไม่ใช่ PDF (probability density function) เพราะ PDF เป็นการบอกว่าจะได้ของครบที่การตี x ตัว แต่ CDF จะบอกเราว่าเมื่อเราตีไปแล้ว x ตัว โอกาสที่เราจะได้ของครบ (นับตั้งแต่การตีตัวแรก) เป็นเท่าไหร่

ยกตัวอย่างการตีความ จะได้ว่า
– PDF ที่ x = 5000 มี P(X=5000) = 0.001 แสดงว่า ความน่าจะเป็นที่ของดรอปครบตอนตีมอนได้ 5000 ตัวพอดีอยู่ที่ 0.001 หรือ 0.1%
– CDF ที่ x = 5000 มี P(X<=5000) = 0.6 แสดงว่า ความน่าจะเป็นที่ของดรอปครบตอนตีมอนไปแล้ว 5000 ตัวอยู่ที่ 0.6 หรือ 60% (อาจจะครบก่อนหน้านี้ก็ได้)

ฟังก์ชันใน Wolfram Alpha ชื่อ NB(r,p) โดยให้ r = จำนวนของที่จะใช้ และ p = drop rate
สำหรับ MATLAB หรือ octave สามารถใช้ nbinpdf และ nbincdf ในการหาค่าจาก PDF และ CDF ได้


ภาพข้างบนแสดงให้เห็นความแตกต่างระหว่าง PDF ที่เป็นการแสดงโอกาสรายครั้ง กับ CDF ที่เป็นการบวกสะสม PDF อีกที จะเห็นว่า PDF มีรูปคล้าย (แต่ไม่ใช่) รูประฆัง ในขณะที่ CDF เป็นรูปตัวเอส (ทั้งนี้ เนื่องจากจำนวนมอนที่เราตีเป็นจำนวนเต็มเสมอ จริงๆ กราฟทั้งสองต้องแสดงจุด ไม่ใช่เส้น แต่ช่างมันเหอะ ไม่งั้นมองไม่เห็น)


Continue reading [Math] How to find drop rate after killing “x” monsters

[Python] ผำควนโดยพอนไธ / Thai Spoonerism with Python

จากโจทย์ที่มีโกนพาสเบ็นหนด ว่วยด้าการสร้างควนผำ http://www.pagist.info/7331317


juannam = len
jemnuantam = int
rut_inpaw = raw_input
def tamkad(kam):
    sara = {'a','e','i','o','u'}
    for akkirata in range(juannam(kam)):
        if kam [akkirata]  in sara:
            return (kam [:akkirata] ,kam [akkirata:] )
    return kam
def pangpayuan(paekyangra, pangyangla):
    (payanchanaektonpayangra, sianglangpaekyangra) = tamkad(paekyangra)
    (payanchanangtonpayangla, sianglangpangyangla) = tamkad(pangyangla)
    return (payanchanaektonpayangra+sianglangpangyangla, payanchanangtonpayangla+sianglangpaekyangra)
def pamkuan(kam):
    pangya = kam.split()
    if juannam(pangya) < 2: #mai tueng sung kom pai mai duan
        return kam
    lamdabkaektipuankamram, lamdabkangtipuankamram = (juannam(pangya)/2-1, juannam(pangya)-1)
    (pangya [lamdabkaektipuankamram] , pangya [lamdabkangtipuankamram] ) = pangpayuan(pangya [lamdabkaektipuankamram] , pangya [lamdabkangtipuankamram] )
    return ' '.join(pangya)
def main():
    jamnuankam = jemnuantam(rut_inpaw())
    for kitam in range(jamnuankam):
        print pamkuan(rut_inpaw())

ป.ล. มันยากอีตรงผวนโค้ดนี่แหละ = =”

[Math] No Free Chocolate. Period.

Alright, I’m so fed up with these “social network shares” about getting free chocolate by breaking a bar and rearranging the pieces, as shown in this video:

Here’s my complaint: I followed the video MATHEMATICALLY, on a paper, and found out the entire bar of chocolate is shortened! Hey! That’s NOT what we call free chocolate!

Diagram disproving the video above

SVG Version

EDIT: It is also noted by @minikoong that my representation has an error. Apparently, the original chocolate bar is nominally 360000 pixels in size, but when cut, the 40-pixel reduction from the top causes the main chocolate bar to reduce to 344000 pixels. According to one-block size of 150*100 = 15000 pixels, there is apparently a (360000-344000+15000)/360000*100 = 0.2778% loss. I admit it is my error in the drawing: the length of “new” chocolate bar should be 862.5 pixels, not 860.