Associate Professor YU Haifeng (yuhf/) 1 Roadmap Research area and example thesis topic What to...

Associate Professor YU Haifeng (http://www.comp.nus.edu.sg/~yuhf/) 1

RoadmapRoadmap

Research area and example thesis topic

What to expect

Factors for successful research

Financial aid


Why do you do research?Why do you do research? Do you feel that many technologies in our society can be

improved by your smart ideas? Doing research gives you the opportunity to impact the industry

and change the world

Doing research gives you the opportunity to have other researchers follow your great ideas, and amplify the influence of your ideas

Overall, you will be able to make impact

Are you curious about the real answers to various open research questions today? Doing research gives you the opportunity to satisfy such

fundamental curiosity as a human being, and to expand the knowledge base of the mankind


Why do research in my area?Why do research in my area? My research area: Distributed computing, distributed algorithms,

and applied algorithms in networking. Overall, focus is on applied algorithmic issues arising from real

systems.

“Algorithmic issues” means my research has a lot to do with algorithms. “Applied” means that those algorithmic issues must be well motivated/justified by real systems.

Doing research in such a research area gives a great opportunity to make impact and at the same time, to satisfy your curiosity Future computer systems (or computational devices) will almost always

be in networks (e.g., Internet of Things)

These systems pose new challenges to my research area, and introduce numerous exciting open research questions

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An example thesis topic of one of my An example thesis topic of one of my current Ph.D. students (Zhao Yuda)current Ph.D. students (Zhao Yuda)

We want to monitor the possibility of landslide after a large earthquake, using wireless sensors See http://www.winetsrl.com/landslide_e.html for an example commercial

system doing this

To do so, we can drop many wireless sensors into a certain region from the airplane, to form a wireless sensor network See http://en.wikipedia.org/wiki/Wireless_sensor_network for what is a

wireless sensor network

Each sensor reports a motion reading, and we want to know the average motion reading in a certain area to monitor possible landslide

Associate Professor YU Haifeng (http://www.comp.nus.edu.sg/~yuhf/)

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An example thesis topic of one of my An example thesis topic of one of my current Ph.D. students (Zhao Yuda)current Ph.D. students (Zhao Yuda)

Let’s re-cast the earlier setting into a research problem…

Goal: Total N nodes. Each node has a binary value, root node wants to compute the sum of all values This is the base case -- Once we can do this, we will be able to easily compute the average

among all values, where each node has a floating-point value

Performance measure: We want to minimize the number of bits sent by each node when computing the sum

root

0

1

1

1

1

0

1


Example thesis topic: Example thesis topic: Existing approaches for computing sumExisting approaches for computing sum

Approach 1: Send/relay all N values to the root A node near the root may need to send/forward over N bits

Approach 2: Use a spanning tree and do aggregation Illustrated in the following animation

Each node sends at most O(logN) bits

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root

0

1

1

1

1

0

1

11

30

2

11

sum = 0+3+2 = 5


Example thesis topic: Example thesis topic: Failures make things interesting…Failures make things interesting…

Tree-based aggregation cannot tolerate failures

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root

0

1

1

1

1

0

1

11

30

11Xsum=0+3=3

wrong result!

failed

Can you design an efficient protocol for computing Sum so that each node only sends O(logN) bits and can tolerate arbitrary failures?


Example thesis topic: Example thesis topic: So what is the thesis topic?So what is the thesis topic?

Design better fault-tolerant protocols for computing Sum

Prove lower bounds on the number of bits that a node needs to send

In case you are curious We have proved that to compute Sum in a fault-tolerant way,

some node will need to send

So it is impossible to design a fault-tolerant protocol where each node only sends O(logN) bits…

8

bits

N

N2log



RoadmapRoadmap


What to expect


Financial aid

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Style of Research in Our GroupStyle of Research in Our Group For our research, novelty is more important than sheer

amount of engineering My group works in a smart and creative way

For our research, 1 hour of creative thinking can worth 10 hours of drilling

Your creative thinking will be a key asset in my group

I care about research output more than how the student generates such output For example, I don’t care much about how long you stay in lab or

how you spend your leisure time


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What to Expect from MeWhat to Expect from Me I usually work with my students on research problems for which we

already have unique insights and clear advantages over other research groups in other universities

I do research TOGETHER with the student, instead of just supervising them I spend a lot of time with my students, prove many theorems together,

solve hard steps if they cannot solve those, and write our papers together

Of course, if the student prefers to do most the work alone, I won’t disturb him/her either

The above two factors ensure that my students have high success rate of solving the research problems So far (at the time of my writing), the vast majority of my papers get

accepted upon the very first time we submit them for publication


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What I Offer to StudentsWhat I Offer to Students Opportunity to do cutting edge research and achieve results that nobody in

the world (not just in Singapore or Asia) has achieved

Example 1: My students and I proposed a new concept of Error Estimating Coding (EEC) for wireless networks. EEC offers a new functionality/overhead tradeoff that is different from the classic error correcting codes (which had been around for more than half a century). The work won the Best Paper Award in SIGCOMM 2010. SIGCOMM is the top conference in networking. This was the first time that this prestigious award was given to researchers outside of the United States.

Example 2: My students and I proved strong results on fault-tolerant community complexity of certain aggregate functions. Our results close an open question over the past decade, and at the same time, open up a new topic ripe with future research opportunities. The work was published in JACM. JACM is often considered as THE TOP publication venue on principles of Computer Science. JACM explicitly states that it publishes “the most significant work on principles of computer science”, and only accepts papers that are “among the best papers of the year in its area”.


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What I Offer to StudentsWhat I Offer to Students As evidenced by our top-tier publications, the top-notch research

opportunities you get here will be at the same level as the opportunities that you would get in any top university that you can think of in the world.

In fact, our ultimate goal is for our work to be pioneering and to lead the way for other universities and research groups in the world.

Finally, from a practical perspective, you should understand that when you are looking for a research job, it is your CV (especially your research/publication record) that determines your competitiveness against other people – The Ph.D. diploma, purely by itself, has almost no value.



RoadmapRoadmap


What to expect


Financial aid

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What makes you do successful research hereWhat makes you do successful research here Factors for you doing successful research here

Your logical and creative thinking

Your strong background in mathematics – this is the foundation of all natural sciences

Your strong background in algorithms

General factors Have strong motivation and dedication to do cutting edge

research

Be mature, honest, and responsible (my group has a low tolerance threshold for dishonest or irresponsible behavior, especially related to academic and research integrity)

I can take students with an undergraduate degree in mathematics or physics as well


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Rough Gauge for Students from ChinaRough Gauge for Students from China If you are from China, following are some more specific measures

for you to judge whether you are “strong in mathematics”.

Your math background will be sufficiently strong if back in high school, you were able to get 全国高中数学联赛一等奖 or 全国高中物理学联赛一等奖 or 全国高中信息学联赛一等奖 or prizes at equivalent levels.

If you did not get those, your math background will also be good enough as long as you feel (e.g., by comparing yourself with those who did get those prizes) that you would be able to get those if you tried hard enough or if you got the training that other people got.

If you are not sure, you can always come and ask me.


Financial Aid from the University Financial Aid from the University (At the time of my writing)(At the time of my writing)

Research Scholarship (http://www.comp.nus.edu.sg/graduates/scholarship.html): “The Research Scholarship will carry monthly emoluments, plus full tuition fee

subsidy”. “Each scholarship holder will receive a non-taxable monthly allowance of S$2,000 (for international students) and S$2,500 (Singapore Citizens). Graduate students who passed their PhD Qualifying Examination will be awarded an additional top-up of S$500 per month (for two years) during their PhD candidature.”

There are other scholarships and fellowships (http://www.nus.edu.sg/admissions/graduate-studies/scholarships-pgf.php and http://www.nus.edu.sg/ngs/NGSS.html) with month stipend up to S$3,200

17Associate Professor YU Haifeng (http://www.comp.nus.edu.sg/~yuhf/)

Associate Professor YU Haifeng (yuhf/) 1 Roadmap Research area and example thesis topic What to...

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