Porce's Epistemology

Cross-Layer Design Considerations

porce — Fri, 17 Dec 2010 14:18:19 -0800

Title: Cross-Layer Design Considerations

Jiwoong Lee, University of California, Berkeley

ABSTRACT

INTRODUCTION

The prosperity of the Internet successfully produced the wide deployment of the network infrastructure, enormous number of the network users, and still promising vision on the network industry. In addition to this, the desire of cordless communication has recently been propelled so that there exist a huge trend of technical and academical challenge in wireless communications. Meanwhile the networking protocols and systems have been optimized for conventional wired networks, the wireless medium shows somewhat fundamentally different characteristics so that the legacy protocols and systems do not perform in the optimized sense.

RELATED WORK

WHAT IS ARCHITECTURE

A better understanding of the notion of architecture is required to have a firm base to discuss cross-layer design. Three basic model of architecture can be discussed. The first model is called as brick model. Brick model is used most commonly and most robust in a simple design. Next model is called spagetti model. Spagetti model does not have a layered architecture at all inside. Rather, its functionalty is totally mixed. Its implementation can be really messy. However if carefully designed and implemented, this model can have the optimal performance. The final model, which is a graphical understanding of the cross-layer design, is the jigsaw model. Jigsaw model is placed in the middle of brick model and spagetti model. It has dividable components but their interaction is much more involved than brick model, less than the spagetti model. From this graphical representation, we can acquire two important perspectives of the cross-layer design. First perspective is that the adjacent layers have much larger interface area between them than the brick model that has flat interface area. As will be discussed later in this paper, this expanded area implies the change of abstraction model of each layer. In other words, a layer 'understands' its adjacent layers with more verbose parameters. The second interesting perspective on this is the conglomeration of the functionalities which were believed to belong to different layers. This conglomeration of functionalities have not been recognized widespread. However, this must be the essencial understanding as well as the expanded interface area. One good example of this conglomeration is the merged MAC forwarding-Network routing.

There was a research that emphasized the importance of architecture; the architectured design was believed the key to make it survive and thrive. In [Kumar2005] four examples were introduced as successful architectures. They were Von Neumann architecture which initiated the modern computer architecutre and has been unchanged, the OSI network architecture which has been the fundamentals to understand complex network systems although its implementation has never been used, the Source-Channel separation architecture which was introduced by Shannon and is still regarded as one of the most excellent achievement in communication theory, and finally the feedback control system which is necessary in any form of control system. There are no argue point in that those four examples are fundamentally important and have been rigid bases. However one surprising thing is that except feedback control system, other three architectures are not relatively old enough. Von Neumann architecture was introduced in 1963, OSI 7 Layer architecture was finalized as an international standard in 1988, and Source-Channel separation was pulicized in 1949. Therefore we have to acquire a sense that what we have been believing as an unbreakable fundamental architecture were actually young enough to be challenged by a new architecture.

WHAT IS LAYERING

Before introducing a new challenger, we might as well contemplate the concept of layering design. Layering can be understood in following ways. They are essentially the same.

- Layering is isolating conceptually different functions

- Layering is decoupling the complicated problem into smaller ones

- Layering is decomposing the problem space into subspaces

The advantage of layering is it enables modular design. Optimization of the overall complicated system is reduced to the optimization of each simple module. Modular design enables the reusability of the design, implementation, and operation. It even enables the modular understanding of the system.

As a result of layering, abstraction of layers are produced. Interface of the layer handles this abstaction to understand, communicate with the adjacent layers.

Layering is the product of 'divide-and-conquer' philosophy. This was originally the military strategy. What this strategy claims is that when one fight with 10 enemies, it is easier to fight with one by one rather that fight with ten at the same time. This strategy was later incorporated into the algorithm design paradigm. As one can easily imagine, this is a useful and powerful strategy. Now I have a question for you. Does this strategy always work ? The correct answer is no. This strategy works only when the cost of combining is less than the cost of dividing and solving. In other words, if the tackling the whole problem is more efficient than dividing the problem space and solving each divided subspace, then layering approach might not work. This is the philosophical basement of the cross-layer design.

GOAL OF CROSS-LAYER DESIGN

In contrast to the approach of layering design, the aim of the cross-layer design is to couple some functionalities of heterogeneous layers to boos the systm-wide performance by taking advantage of joint optimization. An interpretation of the trend of the cross-layer design is that we have faced the limit of the divide-and-conquier strategy at the emergence of wireless communication, in the sense of the legacy layering model. Therefore to increase the system-wide performance, we need the expanded abstaction of each layer in the interface or more organic model in which every small components can work with others.

A recent research [Iyer2003] described the possible cross-layer interactions through the expanded layer abstaction. For example, transmission power has been conventionally the internal parameter of the physical layer and has not been shared with other layers. In a cross-layer design, however, the transmission power can be in higher layer; network layer can determine its route based on its current trasmission power. Another example is that physical layer uses the number of the retransmission performed in MAC layer in change its modulation scheme which provides more robust detection at the cost of power consumption.

TENSION

It is true that there is a tension in diving into the cross-layer design since it requires, by definition, the break of the conventionally defined layered architecture. Breaking this boundary can break the modularity, compatibility or guaranteed minimum performance as well.

COUNTER-EXAMPLE

This tension is worthy of a few more words since the expected worries are not a total illusion. A good example was analyzed in [another Kumar2005]. When a rate adaptive MAC, wich adjusts its data rates based on the channel quality information delivered by the physical layer, is used with the network layer's minimum-hop routing, the overall throughput of the system was degraded up to 55% in comparison to the case that does not use the rate-adaptive MAC. A rate adaptive MAC and minimum hop routing were developed independently but when they were used cooperatively, the result of the cooperation was worse. This is a good example showing that cross-layer performance optimization requires cross-layer engineering.

LIMIT

Therefore we had better point out the limit of the cross-layer design not to repeat the same cross-purpose optimization. The biggest limit of the cross-layer design is this design paradigm is quite new so that the consequence of the cross-layer design is not easily imagined like a new born baby. When a new design is combined with other layers' protocols, traffic pattern, user behavior, unexpected conseequences will be brought out, while it can be good or bad. The second limit of the cross-layer design is the lack of the compatibility with the legacy protocol stack. The third limit is the possible lack of modularity. The fourth limit is its longevity. The final limit is essentially not a limit; it is a possibility. A recent research showed the performance improvement of the cross-layer design is constant times of that of the layered-design

CONCLUSION

These are a few of porce's favoriate things

porce — Fri, 17 Dec 2010 14:03:46 -0800

Google chrome: For its speed
San Diego SeaWorld: For its Shamu
Berkeley's Berkeley Bowl Grocery Store: For its stunning diversity and 'old-market' style
Apple Macbook Pro: For its superb stability and user interface convenience
The Getty Center at Los Angeles: For its founder's unprecedented service to general public
Inchon International Airport: For its clean, convenient, and luxurious quality of all facilities.
Apple iPhone 3G: For its contribution to the smarter mobile world
Peet's Coffee Eggnog Latte: For its super thickness in its kind.
Two wines: Domaine du Grand Montmirail Recolte 2007, Vacqueyras, and Narsai David Estate 2004, Cabernet Sauvignon, For their full of light flavors

How to do a Good Research

porce — Fri, 17 Dec 2010 13:51:34 -0800

1. Survey

'Surf' the references of references

Read Tutorial

Read 'Survey' paper that has done the homework on behalf of you

2. New field. New solution concept. New formulation

It provides a 'recipe' how to formulate, what to assume, and what to show.

Academia stimulus

3. Mathematical techniques.

4. Imagination

Just imagine what would be great if you discover about nature, human mind, or complex system.

Imagine what would be surprising when achieved or showed.

Science is a process to augment evidence for hypothesis that does not have enought evidence yet.

Hypothesis only comes from imaginative power, but not the deductive reasoning.

5. Proof

By inspection:

This is the most primitive way of proving something. This purile technique is sometimes, but not widely, used in practice.

By example:

By Logic system

Existence ( Presence )

This proof technique is the most surprise to me in my life time. I recall I encountered this technique in the freshman's Calculus class when one studies Augustin Louis Cauchy's epsilon-delta definition of limit. Before this I was never taught about 'existence' of 'presence', and therefore it sounded very weird.

In fact, all people can define what a natural number is, but nobody properly defined its existence. We always implicitly assume the existence of natural number 11, and no one doubts about it. Further, one could define a negative number, but no one knows the existence of that negative number. What is -11? More fundamentally, what is 0? Is it nil? Is it non-existence? What is it?

Further,

정부/산업 장학금 제도

porce — Fri, 17 Dec 2010 13:45:32 -0800

[해외 명문대 공짜유학 가기] 정부·단체 활용하면 큰 도움 받을 수 있어
등록금, 학비, 생활비, 왕복 항공료, 정착금, 의료비, 기숙사비까지 지원해

외국 정부
일본ㆍ독일ㆍ프랑스ㆍ영국은 외국인 장학제도 운영

외국 정부 장학금과 국내 단체 장학금, 외국 단체가 지원하는 장학금을 받으면 자비를 들이지 않고도 외국 명문 대학 또는 대학원으로 유학을 갈 수 있다. 외국 정부 지원 장학금은 학비 일부를 지원해주는 것에서부터 등록금, 학비, 생활비, 왕복 항공료, 정착금, 기숙사비, 의료비까지 포괄적으로 지원해주는 것 등 다양한 종류가 있다.

국내에도 우수한 학생을 위해 장학금사업을 하고 있는 기업과 비영리 기관이 여럿 있다. 국내 단체 장학금은 대부분 학비 전액과 학위 과정이 끝날 때까지 생활비를 지원해준다. 일부 기업체 장학금은 유학 후 본사에 입사하는 것이 의무사항이지만, 그렇지 않은 경우가 더 많다.

외국 주요 단체가 제공하는 장학금도 다양하다. 그 중에는 로타리 장학금, 풀브라이트 장학금, 동서문화센터 장학금처럼 비교적 알려진 것도 있지만 웨슬리안대학 프리먼 아시안 장학금, 리치먼드 한인회 장학금처럼 잘 알려지지 않은 것도 있다.

일본 문부과학성 초청 연구장학금 (www.kr.emb-japan. go.jp/cult/cul_study_national. htm, 02-765-3011~3)

일본 문부과학성이 지급하는 장학금. 120명 정도를 선발해 매달 17만2000엔을 생활비 명목으로 지원하며 등록금, 학비, 왕복 항공료, 정착금(2만5000엔), 기숙사비, 의료비 일부까지 포괄적으로 지원해준다. 대한민국 국적을 가진 자로서 해외 유학에 결격사유가 없는 만 35세 미만인 자를 대상으로 하며, 최종 학교 성적이 100점 만점 기준, 평균 80점 이상이어야 한다. 지원일 현재 휴학 중인 자는 지원할 수 없다.

독일 학술교류처(DAAD) 장학금(Forschungs Studienstipendium, www.daad.or.kr, 02-324-0655)

독일 학술교류처에서 운영하는 석사 과정 프로그램. 독일 각 대학 및 기관에서 연구하는 외국인 신진 학자를 대상으로 한다. 2006~2007년의 경우, 한국에 배당된 인원은 9명. 지원분야는 예술을 포함한 모든 분야. 석사, 박사, 박사후 연구과정(Postdocs) 지망자도 신청할 수 있다. 한 달에 715~975유로(과정·경력에 따라 차등지급), 왕복 항공료, 의료보험료 보조금, 어학코스 비용, 가족지원금, 연구지원금 등을 지원한다. 신청 당시 만 32세 미만(음악부문 지망자는 만 28~30세)이어야 하며, 신청 당시 이미 독일에서 1년 이상 체류한 사람은 자격이 없다.

영국 외무성 장학금(www.britishcouncil.or.kr/chevening, 02-3702-0613)

영국에서 석사, 박사, 박사후 과정을 이수하려는 사람을 대상으로 영국 외무성이 지급하는 장학금. 선발 인원은 40명 안팎. 1년간 학비를 지급하며, 우수한 지원자에겐 예외적으로 생활비를 지급해준다. 대한민국 국적 보유자여야 하며, 일정 수준 이상의 영어 능력(IELTS 6.5 이상)을 갖춰야 한다. 학위 취득 후, 정당한 연장 사유가 없는 한 한국으로 돌아와야 한다.

영국 ORS 장학금(Overseas Research Students Awards Scheme, www.universitiesuk.ac.uk/ors/, 02-3702-0613)
외국 학생의 학비가 상승함에 따라 영국 대학에서 공부하는 외국 학생의 부담을 덜어주기 위해 1979년 생긴 장학금. 영국 학생과 영국에서 공부하고 있는 외국 학생의 학비 차액을 보조해주기 위한 성격이다.

프랑스 파스퇴르장학금(www.bref.co.kr/education/ Bourse. htm, 02-317-8500)

프랑스 외무부가 한국 학생을 위해 신설한 장학금. 한국의 젊은이에게 프랑스에 대한 이해를 돕고, 지적 발전의 기회를 제공하기 위한 것. 이미 학위를 받고 프랑스 고등교육기관(대학, 그랑제꼴, 국립 혹은 사립 연구기관 등)에서 연구를 계속하려는 사람을 지원 대상으로 삼는다.

프랑스 파스칼 장학생(www.edufrance.or.kr, 02-317-8569)
프랑스의 천재적인 학자 블레즈 파스칼의 이름을 딴 장학금. 매년 한국의 우수 학생을 유치해 프랑스 각 대학 및 그랑제꼴 석·박사 학위를 취득할 수 있도록 지원한다. 주관 기관은 프랑스 교육부와 외무부가 창설한 공공기관인 에듀프랑스로, 이 기관은 프랑스의 고등교육을 장려하며, 세계 각국의 학생이 프랑스에서 생활하며 공부하는 것을 지원한다.

유럽 듀오-코리아장학금(DUO-Korea Fellowship, www.asemduo.org/main.htm, 02-720-6712~3)
한국과 유럽 25개 아셈회원국(그리스ㆍ덴마크ㆍ벨기에ㆍ프랑스ㆍ핀란드ㆍ독일ㆍ영국ㆍ이탈리아ㆍ룩셈부르크ㆍ네덜란드ㆍ포르투갈ㆍ스페인ㆍ스웨덴ㆍ아일랜드ㆍ오스트리아ㆍ체코ㆍ사이프러스ㆍ에스토니아ㆍ헝가리ㆍ라트비아ㆍ리투아니아ㆍ몰타ㆍ폴란드ㆍ슬로바키아ㆍ슬로베니아) 사이의 교류 증진을 목적으로 하는 장학금. 학생, 교사 및 교수가 ‘한국인 1명-유럽인(아셈 국적 소지자) 1명’으로 한 조를 이루어 맞교환하는 경우, 듀오-코리아가 양측 대상자 모두에게 장학금을 제공한다. 지원자는 지원 당시의 신분을 교류가 끝날 때까지 유지해야 한다. 예를 들어, 학생 지원자는 지원 시점부터 교류가 끝날 때까지 학생으로 있어야 한다. 학생에겐 4개월(1학기)에 8000유로, 교사·교수에겐 1개월에 6000유로를 현금으로 지급하며 사용처에 제한을 두지 않는다.

국내 단체
기업체가 운영하는 장학재단이 다수

국비 유학(국제교육진흥원, www.ied.go.kr, 02-3668-1300)

역사와 권위를 자랑하는 대한민국 정부 장학금. 국제교육진흥원 주관으로 3월 초 공고를 내고 5~6월 시험을 치른다. 선발인원은 매년 40명(학위과정 33명, 전문요원과정 7명) 선. 1년에 최대 3만8000달러(미국 기준)까지 지원한다. 인문, 사회, 이공계열 모두 지원 대상. 1차 시험과목은 국사와 해당 외국어. 유학 중 또는 유학 후에 이행해야 할 의무사항은 없다.

삼성 이건희 장학재단(삼성장학회, www.slsf.or.kr, 02-751-8811)
전공분야나 선발인원이 정해져 있지 않은 것이 특징. 국가별 또는 대학별 선발인원 역시 사전에 정해져 있지 않다. 단 MBA, 로스쿨, 의과대학원 및 어학과정은 지원되지 않는다. 최대 연 5만달러까지 지원. 입학연도 기준으로 병역 미필자의 경우 학사 만 21세·석사 만 25세, 병역을 마친 경우엔 학사 만 25세, 석사 및 박사 만 30세 이하로 연령제한이 있는 것이 특징.

관정 이종환 교육재단(www.ikef.or.kr, 02-753-6269)
삼영화학그룹 이종환 회장이 사재 3000억원을 출연해 설립한 장학금. 미국, 영국, 독일, 프랑스, 중국 등 해외 각국에서 공부할 한국인 장학생을 대상으로 한다. 매년 100명 가량 선발해 연간 최고 5만달러까지 장학금을 지급하고 있다. 선발되면 학업 향상 정도에 따라 학부 과정 4년, 석사 2년, 박사 과정은 3년 동안 지원받을 수 있다.

한국고등교육재단(www.kfas.or.kr, 02-552-3641)
아무런 의무사항이 없는 것이 특징. 사회과학·자연과학·정보통신 분야를 중심으로 매년 약 30명을 선발한다. 학비, 생활비 및 보험료를 포함한 전액(2005~2006년 기준, 5만달러 규모)을 지급하며, 유학 대학에서 장학금을 받는 경우엔 학비나 생활비 또는 연구지원비만을 지원한다.

한국과학재단 대통령 과학 장학생(www.kosef.re.kr, 042-869-6114)
고등학교 졸업 예정자만을 대상으로 수여하는 장학금. 해외(연 10명 내외, 최대 연 5만달러)와 국내(연 140명 내외, 연 1000만원 규모)로 나눠 선발한다. 수학 및 과학 분야의 탁월성 및 발전가능성을 선발의 주요 기준으로 삼는 것이 특징. 해외 장학생에게 4년간 학비, 체재비 등 최대 5만달러를 매년 지급한다.

태광그룹 일주학술문화재단
(www.taekwanggroup.co.kr/tg_c/ c.html, 02-3406-0487)
태광그룹에서 지원하는 장학금. 박사학위 과정을 대상으로 한 해에 4명 정도를 선발, 5년간 매년 3만달러를 지급한다. 관련 전공은 경영, 경제, 사회, 인류, 동양사, 응용, 재료, 화학공학.

미래에셋 장학금 (http://fund.miraeasset.com/fundapp/ global_people/view.jsp, 02-3774-1500)

연 5만달러 이내에서 학비, 생활비를 지원한다. 선발인원은 30명 내외. 과거 전공 및 성별에 관계없이 경제, 경영, 금융, 파이낸스 관련 학부·대학원 지원자를 대상으로 한다. 졸업 후 미래에셋 입사 의무가 없으며, 지원국가에도 제한이 없다. 가정형편이 어려운 사람에겐 가산점이 부여된다.

외국 단체
주로 미국 회사 재단이 많아

로타리 친선사절 장학금(www.rotarykorea.org/scholarship, 02-738-1051)
로타리재단에서 지급하는 장학금. 재단 각 지구에서 선정해 최대 연 2만5000달러까지 지급한다. 대학 과정을 2년 이상 수료했거나 고등학교를 졸업한 후 인정하는 직업 분야에서 2년 이상 상근한 사람이 대상이다. 로타리 회원 또는 회원과 친척관계인 사람, 현재 유학 중인 사람은 대상에서 제외된다.

풀브라이트 대학원 장학 프로그램(www.fulbright.or.kr/ 한미교육위원단, 02-3275-4000)
미국 풀브라이트 장학 위원회가 수여하는 장학금. 인문·사회과학·예술분야를 대상으로 한다. 한·미교육위원단이 심사를 대행, 심사위원회의 추천에 따라 후보자를 선발한 뒤, 풀브라이트 재단 본사가 최종 선정한다. 선발인원은 15명 안팎. 학비(평균 2만5000~3만달러), 매달 생활비 950~1300달러, 왕복 항공료를 지급한다. 대한민국 국민이어야 하며, 이중국적자는 자격이 없다.

동서문화센터 장학금(www.eastwestcenter.org/한미교육위원단, 02-3275-4000)
1960년 미 의회가 아시아·태평양 국가와 상호이해와 협력을 촉진하기 위해 설립한 동서문화센터의 국제 장학금. 한·미교육위원단이 선발업무를 대행한다. 하와이대학 등록금, 의료보험, 도서구입비, 기숙사비 또는 주거비 보조, 월 생활비 등 일체의 경비가 지원된다.

케임브리지 문화재단(홈페이지 없음. 학교로 우편발송 뒤 추천받는 형식으로 선발, 02-501-6911)
미국 대학원 석·박사 과정 입학이 확정된 사람을 대상으로 1년에 2만5000~5만달러를 지급한다. 서류·면접을 거쳐 매년 10명 안팎 선발. 지원 금액은 대학별 등록금, 전공분야, 주거비 등을 참고해 차별화될 수 있다. 대한민국 국적보유자를 대상으로 하며, 국외 영주권자나 이중국적 보유자는 제외된다.

웨슬리안대학 프리먼 아시안 장학금(www.wesleyan.edu/admission/international/ freeman.html, Korea AIG General Insurance Seoul, 02-2260-6802, sujin.yim@aig.com)

아시아에 오랫동안 거주했던 AIG 그룹 창업자이자 학자 맨스필드 프리먼의 유증으로 세워진 재단. 미국과 동아시아 국가의 관계 증진을 위해 장학금을 수여한다. 지급 대상은 중국, 홍콩, 인도네시아, 일본, 말레이시아, 필리핀, 싱가포르, 한국, 타이완, 태국, 베트남 학생. 대학 4년 학비를 모두 지원한다. 단 프리먼의 모교인 웨슬리안대학(Wesleyan University)에서 공부해야 한다.

한·미장학재단 장학금(www.kasf.org, 1-301-593-4900)
워싱턴에 본부를 둔 한·미장학재단이 미국 전역의 대학생, 대학원생, 고등학생에게 수여하는 장학금. 신청마감은 매년 2~3월경. 미국 전역에서 250여명을 선발해 장학금을 지급한다.

주미 대사관 재미한인 장학금 (www.koreaembassyusa.org/han_ education/kor_scholarship.asp?subgubun=3, 1-202-939-5681)
한·미수교 100주년을 기념해 1981년 설립된 장학금. 대상은 대학 이상 재학생(장애학생, 예체능계는 고교생 포함).
최근 1년간 GPA 성적이 3.5 이상(예능계 3.0)이어야 한다. 지원서, 성적증명서, 추천서, 에세이 등 관련 서류를 각 지역 총영사관 교육담당자에게 제출하면 된다.
유학생을 포함해 매년 80~100명에게 1000달러씩의 장학금을 지급한다.

미주 세종장학재단(www.sejongscholarship.org/, 1-443-414-4209)
메릴랜드 지역에서 사업체를 운영하는 사람이 모여 설립한 장학금. 올해는 미주 전체에서 35명의 한인 학생을 선발, 모두 4만달러의 장학금을 전달했다. 장학금 규모가 매년 증가하고 있으므로 눈여겨봐야 한다.

한·미여성재단, 워싱턴 여성회 장학금(www.okaw.org, 1-703-573-9111)
국제결혼을 한 여성의 모임인 한·미여성재단과 워싱턴여성회가 1990년부터 수여하는 장학금. 한인 학생뿐 아니라 한국 혼혈아의 미국 유학을 지원하고 있다.

리치먼드 한인회 장학금(www.kasgr.org, 1-804-225-1399)
리치먼드 지역의 한인단체가 운영하는 장학금. 18명에게 1만6000달러 규모의 장학금을 지원했다.

메트라이프 장학금(www.metlife.com/scholar, 1-888-638-1947 구내번호 13)
금융사 메트라이프가 이민자의 공헌을 기리기 위해 마련한 장학금. 미국 학제를 기준으로 6∼8학년, 9∼12학년 두 개 분야로 나눠 에세이를 모집, 우수작에 연 1000∼1만달러씩 총 25만달러의 장학금을 수여한다.

맥도날드 아태계 장학금(www.rmhc.com/rmhc/index/ programs/rmhc_scholarship_program.html, 1-630-623-7048)
로널드 맥도날드 하우스 장학재단(RMHC/ASIA Scholarship)이 주관. 커뮤니티 봉사활동이 뛰어난 아시아·태평양계 12학년 학생에게 주는 장학금이다. 지급 규모는 1인당 1000달러.

메릴랜드 패스웨이(Maryland Pathway) 장학금
미국 메릴랜드대(UMD)가 저소득 가정(4인 가족 기준 연소득 2만1000달러 미만) 학생의 학비를 지원해 주는 장학제도. 저소득층 학생이 주당 8∼10시간씩 일하면 학비 전액을 지원해준다.

마이크로소프트 장학금(www.microsoft.com/college/)
마이크로소프트사가 제공하는 장학금. 국적에 관계없이 미국 대학에 재학하기만 하면 누구나 지원할 수 있다. 1년간 대학 등록금을 지불하며, 여름방학 동안 MS사에서 인턴으로 일할 기회도 주어진다.

코카콜라 장학재단 장학금(www.coca-colascholars.org)
코카콜라 장학재단(Coca-Cola Scholars Foundation)이 대학 진학을 앞둔 고교 졸업반 학생을 대상으로 운영하는 장학제도. 4년간 전국 장학생 50명에게 2만달러씩, 지역 장학생 200명에게 4000달러씩 지급한다.

액사 장학금(www.axa-achievement.com, 1-800-537-4180)
투자금융사 ‘액사(AXA)’가 대학 신입생을 대상으로 매년 선발해 지급하는 장학금. 지원자격은 시민권자 또는 합법적인 외국인 거주자로, 미국 대학에 진학 예정인 고교졸업반 학생이다. 지급 규모는 1인당 2000 달러.

아시안 아메리칸 언론인협회 장학금(www.aaja.org, 1-415-346-2051)
아시안 아메리칸 언론인협회(AAJA)가 지급하는 장학금. 저널리즘을 전공하는 아시아 또는 아메리카 출신 대학생(대학원생)을 대상으로, 1인당 최대 연 5000달러까지 지급된다. 신청마감은 4월이다.

타이레놀 장학금(Tylenol Health Scholarship, www.scholarship.tylenol.com,1-877-TYLENOL)
맥닐 제약사가 의료분야 대학생을 중심으로 지원하는 장학금. 1인당 최대 1만달러까지 지급된다. 신청기간은 매년 상반기.

Old time Bookmarks

porce — Fri, 17 Dec 2010 13:42:36 -0800

::Berkeley Courseworks

Spring 2007 Stochastic systems: Estimation and Control
Reference Site
Spring 2007 Statistical Learning Theory
Reference Site
Spring 2007 EE298-2 Net/Com/Dsp Seminar

Fall 2006 IEOR162 Linear Programming
Fall 2006 IEOR262A Mathematical Programming I
Fall 2006 EE226A Random Processes in System
Fall 2006 COLWRIT1 English Writing
Spring 2006 EE224B Fund. of Wireless Comm
Spring 2006 EE228A High Speed Comm Network
Spring 2006 EE290Q Wireless Sensor Network
Fall 2005 EE221A Linear System Theory
Fall 2005 EE226A Random Processes in System

UC Berkeley EECS General Course listings

::Reference Courseworks

UCB CS294 Sensor net Seminar
UCB CS268
UMD CS711 Computer Networks Reading List
Stanford EE360 Advanced Topics in Wireless Communications
CMU Computer System Lectures

Toys:: WienerFilterTestApplet DSB-SC-AM

::Research

Advisor Prof. Jean Walrand
My website

CFP for Mobile Network Control Comsoc Conference Date

Com/Net/DSP Seminar List
CISTRIS Seminar List
BioEngineering Seminar List
EECS Event Calendar
Network Economics Group

IEEELibrary

TeachingResourceCenter

GeneralCatalog OnlineClassSchedule BearFacts InfoBears
CARS FinancialAidOffice Bookstore

IFL(Internet Faculty Library) NTIA_Freq_Alloc Dr.Math Mathworld PlanetMath
ProbabilityCoursesMaterials
MatrixReferenceManual FreeTechBook LongTerm
TrafficStatistics
OCW BMRC IEEEXplorer KERIS SPEC CFPForWirelessAndMobileNetwork
Routching.org GooleScholar TLDs

Historical Papers

New Student Services: http://nss.berkeley.edu/     NSF REU Program: http://www.nsf.gov/home/crssprgm/reu/start.htm    Office of Admissions: http://www.uga.berkeley.edu    Office of the Registrar:  http://registrar.berkeley.edu/     Office of Undergraduate Research: http://research.berkeley.edu    Online Reader Application:
http://www.eecs.berkeley.edu/Scheduling/EE/ta_applications.shtml    Online Schedule of Classes: http://schedule.berkeley.edu/    Re-entry Student Center: http://reentry.berkeley.edu    Registrar Forms:  http://registrar.berkeley.edu/GeneralInfo/elecforms.html    Research Centers and Labs:  http://www.eecs.berkeley.edu/Research/Areas/Centers/    Research Projects:http://www.eecs.berkeley.edu/Research/Projects/    Residence Halls Academic Centers: http://www.reshall.berkeley.edu/academics    Scheduling:  http://www.eecs.berkeley.edu/Scheduling/    Seminar schedule: http://www.eecs.berkeley.edu/Meetings/index.shtml    SISS:  http://www.ias.berkeley.edu/siss/     Student Affairs Office Advising Schedule:
http://www.coe.berkeley.edu/current_students/advising.html    Student Learning Center: http://www-slc.uga.berkeley.edu/slc/    Student Judicial Affairs: http://students.berkeley.edu/sas/SJA/     Student Legal Clinic: http://www.ocf.berkeley.edu/~slc/    Student Parent Project:
http://www.aad.berkeley.edu/uga/osl/aad/aadclass/Studentparent.html    TBP:  http://tbp.berkeley.edu/    Tele-BEARS:  http://registrar.berkeley.edu/StudentSystems/tbinfo.html
http://www.toefl.org     TOEFL:     Transfer Student Center:
http://transfer.berkeley.edu
http://www.berkeley.edu/catalog/    UC Berkeley Catalog:    UCB Parents Network:
http://parents.berkeley.edu/
http://upe.cs.berkeley.edu/    UPE:     URO Program: http://www.coe.berkeley.edu/Students/uro/

::English Resources

General Course listings
CollegeWritingPrograms
ResourcesforWriters
Compleat Lexical Tutor
Longman
LongmanEnglishDictionary
VOA ListeningEnglish EnglishListening ESL Lab
Federal News Radio National Public Radio News

Some old school problems

porce — Fri, 17 Dec 2010 13:36:22 -0800

Q. Xn be an iid sequence of Gaussian random variables with zero mean and variance sigma^2. Yn = (Xn + Xn-1) /2. Define Y = [Y1 Y2 .... Yk]^T. Find joint pdf of Y.

Q. E[X^2 | X+Y] where X, Y are iid Gaussian N(0,1).

Q. TF. X(t), Y(t) are WSS. If they have the same power spectral density, X(t) = Y(t).

Q. Is this true? If rv X, Y have a bivariate normal distribution, correlation is zero if and only if X and Y are indep.

Q. If we have two normal rv X,Y, their correlation can be zero while they are not indep. In this case, does the bivariate normal distribution exist for X and Y ?

Q.When a transmitter sends a signal under a certain modulation with the limited transmit power budget A, the SNR at the receiver will be given as A/No. This SNR is not affected by the modulation scheme. So, if we used BPSK, a^2=A. If we used QPSK, a^2 = A/2. ------> Then why do we define QPSK SNR as 2a^2/No while BPSK SNR as a^2/No ?
----> What about tthe Alamouti's power gain (dividing by two ?)

Q. Is this true? QPSK bit error probability is the same as BPSK bit error probability.

Q. Depending on the approximation, the coefficient value of the error probability varies somewhat a lot. Do we care ?

Q. What is QAM ?

Q. If random vector Z follows Gaussian distribution N(vector m, sigma^2 x I), {Z_i} is IID Jointly Gaussian ?

Q. For Gaussian Random Variable Z_i , if Z_i and Z_j are all uncorrelated for i!=j, are they JG ? are the Independent ?

Q. P[Two type-2 customers arrive before a type-1 customer arrive]

= P[T11>T22]

= P[T11>T22|T12<T11] P[T12 <T11]

= P[T11>T22|T12<T11, T12] P[T

where Tnm means Random variable T for class n and m-th arrival

Q. In callier's textbook, reachability grammian is differently defined from controllability grammian. In continuous case, May I regard these two grammians as the same 'purpose' ? That is, to check the system's complete controllability, may I use either one ?

Q. What is the "singular values" of Reachability Grammian In pp. 228 on the first line of Callier's textbook, it says "For fixed final time t1, all the sinular values of Wr(t0,t1) decrease as t0 increasess towards t1. In particular, if t0<t0', then Wr(t0,t1) >= Wr(t0',t1)"

Q. In EE126 Online Lecture note, PP.149, Example 9.6.3(b), the question was:: Let X,Y,Z be iid and with Binomial(n,p). Calculate L[X|X+2Y, X+3Z].

Lecture note solution:: -6np + 9(X+2Y) + 4(X+3Z) or 13X+18Y+12Z-6np

- The lecture note's solution used the LLSE formula, but improvised an matrix version. (solution attached in the mail)

- When I think about the solution 'intuitively', this does not look like L[X|X+2Y, X+3Z]. (Coefficients are rather high.)

My solution:: = (13X+18Y+12Z-43np)/49

- When I solved this question in a different way, the answer becomes totally different.

- I used the following facts. (I made)

a. L[X|Y,Z] = L[X|Y| + L[X|Z], if E[X]= 0, Y and Z are orthogonal

b. L[X+a|Y] = L[X|Y] + L[a|Y]

c.E[X]=E[Y]=E[Z]= np

<DIV> d.Var[X]=Var[Y]=Var[Z]= np(1-p)

e. L[constant| rv] = constant

f. L[X|aY] = L[X|Y]

The question L[X|X+2Y, X+3Z]

= L[X-E[X] + E[X] | X+2Y, X+3Z]

= L[X-E[X] | X+2Y, X+3Z] + L[E[X]|X+2Y,X+3Z] (by Fact b.)

= L[X-E[X] | X+2Y, X+3Z] + E[X] ( by Fact e.)

L[X-E[X] | X+2Y, X+3Z]

= L[X-E[X] | X+2Y, X+3Z - L[X+3Z|X+2Y]] (Still linear combination)

= L[X-E[X] | X+2Y] + L[X-E[X] | X+3Z - L[X+3Z|X+2Y]] (by Fact a.) (*)

(*) where L[X-E[X] | X+2Y]

= L[X| X+2Y] - L[E[X] | X+2Y]

= E[X] + np(1-p)[5np(1-p)]^(-1)(X+2Y-3np) -E[X]

=(X+2Y-3np)/5 (1)

(*) where L[X-E[X] | X+3Z - L[X+3Z|X+2Y]]

= L[X | X+3Z - L[X+3Z|X+2Y]] - L[E[X] | X+3Z - L[X+3Z|X+2Y]]

= L[X | X+3Z - L[X+3Z|X+2Y]] - E[X]

(*) where L[X+3Z|X+2Y] = 4np + np(1-p) [5np(1-p)]^(-1)(X+2Y-3np)= (X+2Y+17np)/5

and X+3Z - L[X+3Z|X+2Y] = (4X+15Z-2Y-17np)/5

(*) L[X | X+3Z - L[X+3Z|X+2Y]] - E[X]

= L[X | (4X+15Z-2Y-17np)/5] -E[X]

= np+4np(1-p)/5 x 25 [(4^2+15^2+2^2)np(1-p)]^(-1) ((4X+15Z-2Y-17np)/5) -np

= (16X + 60Z -8Y - 68np)/245 (2)

Therefore (1) + (2)

= (49X+98Y-147np)/245 + (16X + 60Z -8Y - 68np)/245

= (65X+90Y+60Z-215np)/245

= (13X+18Y+12Z-43np)/49

Q. Markov Chain: Solution form of the first arrival probability

In Markov chain with forward step probability p and backward step probability q, to calculate probability of first arrival alpha(i) = P[T_N < T_n | X0=i], professor used one-step differential equations.

alpha(i) = q alpha(i-1) + p alpah(i+1), i~=N or n.

alpha(i) = 1 if i=N

alpha(i) = 0 if i=n

For a solution form, professor assumed:: alpha(i) = A + B rho^(i).

How was he able to assume this form suddenly?

Q. Markov Chain: Solution form of the Expected passage time

In the same Markov chain, we calculated the expected passage time to the state a or b. When we define beta(i) = Exp[Ta or Tb | X0= i],wehadthefollowingdifferentialequations(forp=q=1/2)

beta(i) = 1 + 1/2beta(i-1) + 1/2beta(i+1), b < i < a

beta(i) = 0, i=a or b

Professor found that the solution is :: beta(i) = (a-i) (i+b).

How did he get this ?

Q. Markov Chain: Solution form of the Expected passage time

In the same Markov chain, incalculationoftheexpectedpassagetime,ifwehavep!=q!=1/2, what shall be the form of solution beta(i) ?

Q. Markov Chain: Number of the invariant distribution

- If an irreducible MC X is Positive Recurrent and Aperiodic, it has a unique invariant distribution [True/False]

- If an irreducible MC X is Positive Recurrent and Aperiodic, it's invariant distribution is converging.

- If there exists a unique invariant distribution, it is automatically converging

- It is possible that an irreducible, positive recurrent MC X has a non-converging but unique invariant distribution.

- If an irreducible MC X is PR and Periodic, it never has an converged distribution

- If an irreducible MC X is PR and Aperiodic, it always has an converged and unique distribution

Q. If L(y) in decreasing in y,

can we say Z =1 when L(Y)>lambda, or y<y0

Q. Random process

[Q] In Lecture note 12, pp.2 in the middle,

To show Cov(X, X-X^) = Cov(X-X^)

Why E(E[X(X-X^)^T|Y]) = E(E[(X-X^)(X-X^)^T|Y])?

Q. Sufficient Statistic

- Lecture note 10. pp.2, in the middle of Example1, I didn't understand the following equation

P[Z=1|X=0]=P[Z=1|Y=1]P[Y=1|X=0]+P[Z=1|Y=0]P[Y=0|X=0] ... (*)

- I can understand, by the definition of conditional probability, that

P[Z=1|X=0]=P[Z=1|Y=1,X=0]P[Y=1|X=0]+P[Z=1|Y=0,X=0]P[Y=0|X=0] ...(**)

But Why (*) is equivalent to (**)?

[Q] Non-discrete/Non-continuous case expectation

After today's lecture, we had a short talk about E[X|Y=2/3] when P(x,y)=1/2 if (x,y)=(1/2,2/3), and uniform U[0,1]^2 with probability 1/2 otherwise. Can you please write down the derivation of E[X|Y=2/3] ?

Q. Random Process

- Why the U[0,1]^2, have 1/2 prob and (x,y)=(1/3,2/3) prob 1/2 has interesting E[X|Y] ?

Open Issues in Interdomain Routing: A Survey

porce — Fri, 17 Dec 2010 13:27:43 -0800

Excerpts from IEEE Network Magazine, Nov/Dev 2005

Slow Convergence and Chattiness of BGP: Update caused by a link failure and path exploration. And due to Minimum Route Advertisement Interval(MRAI) - 30sec.
Scalability Problems Due to Multihoming
Expressiveness and Safety of Policies: The bad gadget example
Robustness of BGP sessions
Security Issues
Lack of Multipath Routing
Transit through an AS: iBGP issues
Limited Traffic Engineering Capabilities
Lack of QoS Support

Lessons of this matter: The above problems should be handled altogether manner. There is a reluctance of ISP to upgrade.

CIDR_Report http://www.cidr-report.org

하나님이냐 돈이냐

porce — Mon, 13 Dec 2010 03:02:24 -0800

# 돈은 단순한 소유의 문제가 아니고, (우리가) 탐내는 권세의 문제이다

- 현대인에게 있어서 돈은 거룩한 것의 일부를 이루고 있음

- 예수의 병립적 설정: 하나님과 돈(Mammon)

- 문제는 어떻게 돈의 권세를 하나님의 권세에 예속시키느냐는 것이다

1. 성경의 부에 대한 이중적인 견해

2. 보상과 축복으로서의 부

3. 악한 부자의 존재 가능성 / 성경의 평가

4. 부에 대한 성경의 윤리

- 하나님의 주권:

. "그 우편 손에는 장수가 있고, 그 좌편 손에는 부귀가 있나니 (잠3:16)"

. "여호와는 가난하게도 하시며 부하게도 하시며 낮추기도 하시며 높이기도 하시는도다(삼상2:7)"

. "네 재물과 네 소산물의 처음 익은 열매로 여호와를 공경하라(잠3:9)"

. "우리 하나님 여호와여 우리가 주의 거룩한 이름을 위하여 전을 건축하려고 미리 저축한 이 모든 물건이 다 주의 손에서 나왔사오니 다 주의 것이니이다 (대상 29:16)"

. "사람이 하나님의 주신바 그 일평생에 먹고 마시며 해 아래서 수고하는 모든 수고 중에서 낙을 누리는 것이 선하고 아름다움을 내가 보았나니 (전5:18)"

. "곡식과 새 포도주와 기름은 내가 저에게 준 것이요 저희가 바알을 위하여 쓴 은과 금도 내가 저에게 더하여 준 것이어늘 저가 알지 못하도다 (호세아2:8)"

- 부의 상대 가치

. "네 보배를 진토에 버리고 오빌의 금을 강 가의 돌에 버리라 그리하면 전능자가 네 보배가 되시며 네게 귀한 은이 되시리니(욥 22:24-25)

. ".. 나는 이스라엘 자손 중에 네 분깃이요 네 기업이니라(민18:20)"

- 부와 교만의 관계

. "저희가 먹이운 대로 배부르며 배부름으로 마음이 교만하여 이로 인하여 나를 잊었느니라(호13:6)"

. "나는 실로 부자라. 내가 재물을 얻었는데 무릇 나의 수고한 중에서 죄라 할 만한 불의를 발견할 자 없으리라(호12:8)"

- 취득과정의 중요성:

. "망령되이 얻은 재물은 줄어가고 손으로 모은 것은 늘어가느니라(잠13:11)"

. "불의로 치부하는 자는 자고새가 낳지 아니한 알을 품음 같아서 그 중년에 그것이 떠나겠고 필경은 어리석은 자가 되리라(렘17:11)"

- 모범적인 입장

. "먼저 그 나라와 그 의를 구하라. 그러면 이 모든 것을 더하여 주실 것이다(마6:33)"

. "부를 구하지 아니하고 지혜를 구하였은즉 부와 영광도 네게 주노니(왕상3:11,13)"

. "나로 가난하게도 마옵시고 부하게도 마옵시고 오직 필요한 양식으로 내게 먹이시옵소서(잠30:8)"

. "부자 되기에 애쓰지 말고 네 사사로운 지혜를 버릴지어다. 네가 어찌 허무한 것에 주목하겠느냐. 정녕히 재물은 날개를 내어 하늘에 나는 독수리처럼 날아가리라 (잠23:4-5)"

. "곧 허탄과 거짓말을 내게서 멀리 하옵시며 나로 가난하게도 마옵시고 부하게도 마옵시고 오직 필요한 양식으로 내게 먹이시옵소서 혹 내가 배불러서 하나님을 모른다 여호와가 누구냐 할까 하오며 혹 내가 가난하여 도적질하고 내 하나님의 이름을 욕되게 할까 두려워함이니이다 (잠30:8-9)"

. "충성된 자는 복이 많아도 속히 부하고자 하는 자는 형벌을 면치 못하리라(잠28:20)"

5. 가난한 자에 대한 하나님의 입장

6. 불의한 사용에 대한 경고

7. 계시적인 입장

8. 그리스도인의 선택

The Art of Controversy

porce — Thu, 02 Sep 2010 21:13:33 -0700

Arthur Schopenhauer
Die Kunst, Recht zu behalten - The Art Of Controversy

Einleitung	Preliminary	[I]
Eristische Dialektik	Controversial Dialectic	[II]
Basis aller Dialektik	The Basis Of All Dialectic	[00]
Kunstgriffe	Stratagems
Die Erweiterung	The Extension	[01]
Die Homonymie	The Homonymy	[02]
Spezifische Behauptungen des Gegners verallgemeinern	Generalize your Opponent's Specific Statements	[03]
Verdecktes Spiel	Conceal Your Game	[04]
Falsche Prämissen	False Propositions	[05]
Postuliere die These (petitio principii)	Postulate What Has To Be Proved	[06]
Durch Fragen Zugeständnisse erreichen	Yield Admissions Through Questions	[07]
Den Gegner zum Zorn reizen	Make Your Opponent Angry	[08]
Fragen über Umwege	Questions in Detouring Order	[09]
Den Neinsager ausnutzen	Take Advantage of The Nay-Sayer	[10]
Zugeständnisse von Einzelfällen verallgemeinern	Generalize Admissions of Specific Cases	[11]
Wähle polemische Begriffe	Choose Metaphors Favourable to Your Proposition	[12]
Übereinstimmend das Gegenteil verwerfen	Agree to Reject the Counter-Proposition	[13]
Trotz Niederlage den Sieg verkünden	Claim Victory Despite Defeat	[14]
Stelle scheinbar absurde Thesen auf	Use Seemingly Absurd Propositions	[15]
Argumenta ad hominem	Arguments Ad Hominem	[16]
Verteidigung dirch feine Unterscheidung	Defense Through Subtle Distinction	[17]
Den Disput unterbrechen, abspringen oder ablenken	Interrupt, Break, Divert the Dispute	[18]
Allgemeine Abhandlungen statt spezifischer Antworten	Generalize the Matter, Then Argue Against it	[19]
Schlussfolgerungen selber ziehen	Draw Conclusions Yourself	[20]
Faule Argumente mit faulen Argumenten beantworten	Meet him With a Counter-Argument as Bad as His	[21]
petitio principii	petitio principii	[22]
Übertreibungen herausfordern	Make Him Exaggerate his Statement	[23]
Konsequenzmacherei	State a False Syllogism	[24]
Ein einziges Gegenbeispiel genügt	Find One Instance to The Contrary	[25]
Sein Argument gegen den Gegner kehren	Turn The Tables	[26]
Zorn bedeutet Schwäche	Anger Indicates a Weak Point	[27]
Das Publikum, nicht den Gegner überzeugen	Persuade the Audience, Not The Opponent	[28]
Diversion	Diversion	[29]
Autorität als Argument	Appeal to Authority Rather Than Reason	[30]
Davon verstehe ich nichts	This is Beyond Me	[31]
Das Prinzip der Schublade	Put His Thesis Into Some Odious Category	[32]
Theoretisch ja, praktisch nein	It Applies in Theory, But Not in Practice	[33]
Festnageln, nicht loslassen.	Don't Let Him Off The Hook	[34]
Wille wiegt mehr als Einsicht	Will is More Effective Than Insight	[35]
Durch sinnlosen Wortschwall verdutzen	Bewilder Your opponent by Mere Bombast	[36]
Ein schlechter Beweis bedeutet Niederlage	A Faulty Proof Refutes His Whole Position	[37]
Sei persönlich, beleidigend, grob	Become Personal, Insulting, Rude	[38]

Arthur Schopenhauer:	Web Design By http://coolhaus.de 127018
Die Kunst, Recht zu behalten	The Art Of Controversy
Quellen, andere Versionen im WWW: gutenberg.spiegel.de/schopenh/eristik/eristik.htm www.roesch-pr.de/Arthur%20Schopenhauer.pdf	Sources and other versions on the net: manybooks.net/search.php?search=art+of+controversy

J. F. Kennedy's Speech

porce — Mon, 07 Jun 2010 03:29:32 -0700

I know that the University of California will continue to grow as an intellectual center because your presidents, your chancellors and your professors rigorously defend that unhampered freedom of discussion and inquiry which is the heart of the intellectual enterprise and soul of the free universe.

Every great age is marked by innovation and daring by the ability of meet unprecedented problems with intelligent solutions. In a time of turbulence and change, it is more true than ever that knowledge is power; for only by true understanding and steadfast judgement are we able to master the challenge of history.

J. F. Kennedy,
President of the United States

Charter Day Ceremonies
Berkeley, March 23, 1962

Who cannot love this campus?

porce — Mon, 07 Jun 2010 03:22:43 -0700

UC Berkeley campus, May 2010
Left is Sather tower (The Campanile), and right is Bancroft library.

With my iPhone 3G.

What motivates us

porce — Sat, 29 May 2010 22:56:52 -0700

Question: What motivates us?
Wrong answer: Money (reward)
Correct answer: Autonomy, Mastery, Contribution

Phinally Done

porce — Fri, 14 May 2010 16:44:55 -0700

This is an old tradition of UC Berkeley to give out PhD lollipop to fresh PhDs when they file their dissertations. It's a See's candy and my wife's eyes are on it. I should eat it up faster than her.

Best Game Theory Books

porce — Tue, 11 May 2010 19:32:44 -0700

This selection is not for the beginners except for the last one. Rather, these text books provide very deep insight into the modern formulation and concepts in Game Theory.

SH Heap, Y Varoufakis, Game theory: a critical text 2nd Edition, Routledge, 2004
J. von Neumann, O. Morgenstern, Theory of Games and Economic Behavior 2nd Edition, John Wiley & Sons, Inc. 1964
J. P. Aubin, Mathematical methods of Game and Economic Theory, North-Holland, 1982
Y. Varoufakis, Game Theory: Critical Concepts in the Social Sciences, Routledge, 2001
D. Fudenberg, J. Tirole, Game Theory, The MIT Press, 1991
R. B. Myerson, Game Theory: Analysis of Conflict, Harvard University Press, 1991
R. Selten, Rational Interaction: Essays in Honor of John C. Harsanyi, Springer-Verlag, 1992
K. Binmore, Playing for Real: A Text on Game Theory, Oxford University Press, 2007

The Price of 2mm Kidney Stone

porce — Thu, 29 Apr 2010 14:25:04 -0700

It would cost USD 140.00 in Asian countries.

Grad's Weekly Schedule

porce — Thu, 22 Apr 2010 17:34:09 -0700

Double faces of sickness

porce — Fri, 26 Feb 2010 16:46:51 -0800

Sickness is a blessing, as long as you are sure you will recuperate.

I caught a strong cold. Maybe a flu. I have no doubt that the viruses took opportunity of my mental and physical stresses from PhD research. As the end of my PhD program gets close, I feel a big burden to finalize this 5 year program with a grand hope - one single beautiful master piece of work, as a reflection that honestly speaking I did not make one in past.

Counter intuitively intriguing, mathematically spotless, pedantically articulate, academically novel, etc..

To write a good paper is a very very long journey that you usually start with, if fortunate, a tunnel vision. We envision to establish a new theory, a new field, and a new insight to the world.
Creating a novelty is a perpetual headache, a body ache, and a heartache. No body takes my life even if I fail to produce a nice sounding theorem. Even if I succeed, only a small fraction of academia are able to appreciate what we discuss. The rest of the world never care, at least for next 50 years. In fact, my closest people, family members tends encourage me not to attempt ( and play with them instead. )

Then what makes me to devote my entire time and efforts to pursue this lonely journey in academia?

Well, at least I have aspiration to be thrilled at the discovery of the nature, potential contribution to the society, and pleasure of self-achievement. I may affect junior students in a constructive way as a by-product.

Sickness has two facets. In one, it takes away my energy to sit in front of a desk. On the other, it forces me to contemplate what a research's true value is and what a true life means. At my strength, I may want to give up the proof of pending theorem in mind. At the same time, I grow a humble hope that my inner, mysterious ability stands out and shed lights on the path.

We know life is mysterious. I realize my view on life is also mysterious. The most mysterious thing is this sentient awareness of mysterious reasoning about mysterious life.

Sunset over Chicago by kevindooley

A classic Biased coin problem on Steroid

porce — Thu, 18 Feb 2010 17:46:46 -0800

From Julia Robinson Math Festival, MSRI
Making Choices with Biased Coins

In this problem set we will be flipping coins and using them to make various kinds of decisions. A bit of terminology:
• A fair coin is a coin you can flip and it comes up Heads (H) or Tail (T) with equal probability.
• A biased coin with bias p is a coin which comes up H with probability p, and T with probability 1-p.

Problems:

1. Howcanyouuseafaircointochoosebetween4alternatives,uniformly at random? By "uniformly" we mean that you should give no special preference to any of the options. By "at random" we mean that you actually rely on the randomness provided by the coin to ensure that nobody can guess what your choice would be.
2. How about 8 alternatives? 16? 3. Suppose now you have a fair die, which comes up 1, 2, 3, 4, 5 or 6 with equal
probabilities. It's easy to use this die to choose between 6 alternatives, but
how can you use it to choose uniformly between five alternatives? 4. Back to the coin, how would you use a fair coin to choose uniformly between
three alternatives? 5. How many flips does your method take, on average? How many flips does it
require in the worst case?
If you've solved the last part correctly, the next question will make sense.
6. Is it possible to fix this worst case behavior? Can you choose between 3 alternatives with a fair coin using 1,000 flips in the worst case?
7. Let's say you only need to choose between two alternatives, uniformly at random, however the coin you have may be biased, and you don't even know what the bias is. What would you do? Again, what's the worst case behavior?
From now on, we will insist on having methods that only require a specific, finite number of flips. You get to choose how many flips you need but once you did, the method must always work and take no more than this number.
8. Once again you need to choose between 3 alternatives. You may now use two coins rather than just one, and you are free to pick what biases you'd like each of the coins to have (they can be differently biased). In addition, there must be some specific number N such that your method never requires the coins to be flipped more than N times.
9. Now try to tackle 5 alternatives, again using a fixed number of flips and two coins - you can choose what biases you'd like them to have.
10. How about 7 alternatives? 9? Again, you choose the coins, and you decide how many flips you need - but you can never take longer than that.
11. How about 15? 12. Can you do this in general? For every integer m, find a pair of biased coins
such that you can choose between m alternatives, uniformly at random, using a fixed number of flips of the two coins.
Now we're going to raise the stakes...
13. Let's go back to the 3 alternatives. Can you uniformly choose between them with a single coin, and a fixed number of flips? Again, you get to choose which coin you want. (Hint: consider a general coin with bias p, and fix some small number of flips. What are the possible outcomes? Some of them have
the same probability, and since you're free to choose p you can dictate a value for that probability. Which useful value would allow you to simulate the two coins you've used before?)
14. How about 5 alternatives? 15. How about the general case? Think of ways to simulate the two coins you
used above with a single coin. 16. In fact, show that given any finite distribution with rational values, there is a
single coin with which you can simulate that distribution in a fixed number of flips.
If you solved these problems correctly, the biases you used were irrational numbers. This is necessarily the case:
17. Suppose you have a coin with bias p with which you can choose between 2 alternatives in a fixed number of flips. Suppose that the coin is not fair. Prove that p must be irrational.

San Francisco El Dorado

porce — Wed, 17 Feb 2010 00:09:31 -0800

San Francisco Skyline
View from Lawrence Science Hall, Berkeley, CA
Feb 16 2010

Lessons that I should have learned 20 years ago about English

porce — Fri, 05 Feb 2010 15:37:17 -0800

1. Give long time to vowels
Many Asians do not 'pronounce' vowels correctly; All the vowels take just 0.1 sec. No, that's very wrong. Try to give 0.4 sec to each stressed vowel. Non-stressed vowels? Just 0.1 sec is enough. (Note. 0.4 sec is exaggerated. 0.3 should be nought. But practice with 0.4 sec.)

2. Train your lips and tongue by speaking fast
A popular English teacher in China thinks we should speak as fast as possible to learn. In fact, it is Yes and No. It is good only to lip and tongue muscle training. Never good for item 1 and item 3.

3. Think before speaking. Always take 'your' time.
We feel urge to say something to pretend being smart enough. Well, just for passing-by hi-sayer, it is okay. For most of 'conversation', being glib or fast proves nothing. Every sentence coming out of your mouth should always deliver a single message. So don't spit out any subject or verb. Think what message you want to give, and then start to say.

4. Move to a lower frequency tone
I noticed that beginners tend to emit higher frequency, which reflects internal nervousness. As long as you are not answering calls from customers, move your tone to lower frequency. This is more comfortable to hear, and easy to ease oneself.

What Steve Jobs is telling me

porce — Thu, 28 Jan 2010 16:19:47 -0800

Thank you for this, Steve.

You have to trust something - Gut, Destiny, Life, Karma, or whatever.
I have been rejected. but I was still in love.
You've got to find what you love.
Keep looking, and don't settle.
All external expectations, pride, and fear of embarrassment of failure.
You are already naked. There is no reason not to follow your heart.
Death is very likely the single best invention of life.
Don't waste it living someone else's life.

- Steve Jobs, from his speech at Commencement ceremony of Palo Alto Junior College, 2005,

Help Haiti Now

porce — Wed, 13 Jan 2010 13:55:51 -0800

Innocent people are dying.
No food, No electricity, No shelter, No hope they have.

My blood boils. I want to go there. I want to move at least one piece of stone.

But I can't.
No money, no time, no heart hot enough I have. The most poor country has been struck by the saddest disaster. Also I feel disastrous when I learn myself powerless about this.

Year 2010 Wish

porce — Thu, 31 Dec 2009 14:23:40 -0800

Be inspirational.

Count more than ten

porce — Tue, 29 Dec 2009 23:32:34 -0800

My first boy just turned three and he knows how to read and count to 10. Today for the first time I read him numbers larger than 10 from calendar page. I said Eleven, Twelve, Thirteen, Fourteen,... and he repeated after me quite well, until I reached Nineteen. He suddenly screamed 'Stop!!!' and almost ran away. He seemed he couldn't bear those teens..

Red Mustang

porce — Sat, 12 Dec 2009 12:12:28 -0800

I had a visit to Caltech NASA JPL this week. When I got to Burbank airport, I had a surprise gift. It was a red Mustang waiting for me. I was thrilled to enjoy the engine sound and the control in LA highways. Though the reddish color is somewhat showy, it was a fabulous driving.

Why I love Apple

porce — Tue, 24 Nov 2009 14:53:27 -0800

One of my friends messaged me yesterday about how thrilled he is as the iPhone is finally coming to Korea at the end of the month.

Though the monthly premium is still stee

p, I highly encouraged him to get one. Originally I was not a fan of Apple. I had strong bias against it - less open architecture, less number of good software, and pricey pricing.

And - everything got changed when I got my iPhone in 2008. I became an immediate another fanboy of Apple. Soon after I threw away my linksys wifi router and bought even more expensive Apple Airport extreme. I started buy iPhone apps, started to download podcasts, and Macbook Pro. Now I buy legitimate copy of softwares (for my Mac) and subscribe to MacWorld magazine.

OMG, what happened to me? For the last 20 years I have never been enchanted by Microsoft products. I used them massively, sometimes blamed the manufacturer, device driver programmers, and dull colleague programmers. But I have never thought about the exit plan out of it. I had accepted the way as it is, as if it is just a part of normal life.

No, I was totally wrong. There was a bitten fruit. What do you think makes Apple Apple? To me, it is a simple enough answer. It is a sense. It is a sense about a human. A sense about life. A sense about your breath. Microsoft lacks for it. They have intelligence for sure, logic, facts, and great teams of people. It is not about the brain. It is about a sense that is hard to be justified with one's IQ.

Now I am at Starbucks at west gate of my campus. While jotting this down, I looked around my neighbors inside the cafe. Five are with their laptops, and four out of five are using Macbooks. Here is the final punch: three out of them have iPhones right next to laptops. One is using blackberry and one Motorola. One has even an iPod with her iPhone.

Keynote and Latex, by Jens Nockei

porce — Fri, 09 Oct 2009 19:55:34 -0700

Jens Nöckel's Homepage

Computer notes home

Scientific presentations

Table of contents
Starting point Objectives Solutions Caveats, additional utilities	Other presentation tools Why use other tools for presentations? What other solutions are there?

Starting point

This page is about putting maths into computer presentations. Programs like Powerpoint offer a rich variety of features that can (if used judiciously) greatly enhance a presentation. But if you do real science, then there's a good chance that you'll need mathematical equations in your talks once in a while. And that's a need which is met very poorly by Powerpoint.

At this point it should be mentioned that a commercial add-on product has been endorsed by Apple for its '09 version of iWork: MathType by Design Science. This is worth looking at, epecially if you also rely on iWork for actual text processing, or if you are switching from Powerpoint. However, given the free alternatives discussed below, the price of this add-on seems unjustifiably high for use in academia or secondary school education. It's almost as expensive as the whole iWork suite itself!

Mathematics is commonly typeset using LaTeX, but (La)TeX doesn't come pre-installed with Mac OS X. Since the typesetting requirements for a computer presentation are different from those of a scientific paper, some of the suggestions on this page are also intended for people who don't want to install TeX. However, when I think about math content, I usually think about it as originating from some LaTeX process.

The good thing is that under Mac OS X Aqua, many applications can be made to support LaTeX indirectly via the PDF format. If you don't want to install LaTeX, you may find it easier to use dedicated equation editors. Here are some choices:

For instant results, use one of the online tools linked on our departmental web page: Equation Editor Google Gadget.
The Java application GeoGebra has built-in LaTeX syntax parsing to let you annotate graphs. The equations are rendered as bitmaps with rather low resolution, but the program and its general approach are well-suited for middle- and high-school students. Annotated graphs can be copied to the clipboard and pasted into your presentation. If you're a teacher, definitely give this a try!
On a recent Mac, use the pre-installed Grapher in /Applications/Utilities/. It's free and can be used as an input device for math formulas, as this screenshot shows:

You can enter maths in a natural way similar to TeX; as the typed "infinity" shows, the syntax is sometimes different from TeX, but if you can't guess a keyword there's always the pallette at the bottom right. You can copy the Grapher equation as a PDF graphic by right-clicking on it and choosing the appropriate selection from the contextual menu that pops up. I'm saying some more about this on the Pages pages.
Another alternative is Mathematica as a typesetting tool. One advantage of Mathematica is that the structure of its expressions is more semantically organized than in LaTeX, so that export to other formats (such as MathML) is more straightforward. On this page, I will focus on LaTeX because if you only want to learn one input method, LaTeX is the one that will be most useful in general. If you want to be "multilingual" and don't mind using a commercial product, I'd strongly recommend taking a look at Mathematica's capablilites.
What about hand-writing your equations and using that in your presentations? Of course that's what I do in lectures all the time (using a Wacom Pen Tablet since 2006). In a more formal presentation, it can still work quite well to paste your hand-written maths into a slide from a drawing program. But if you want nicely formatted equations, then hand writing is never an ideal starting point. There is hand-writing recognition software that can deal with math expressions, and in particular Windows 7 appears to have made remarkable progress in this arena (as opposed to the Mac where Inkwell has been stagnating). However, I find it awkward to frequently switch back and forth between keyboard and pen tablet; and unfortunately that's precisely what happens when the fine points of your equation get lost in translation.

Now back to the main topic: LaTeX in presentations. If you don't know LaTeX but want to know more about it, you may want to look at my LaTeX page first.

At the bottom of this page I'll refer to some nice free tools that rely essentially on LaTeX and PDF alone to create presentations. This is OK for many occasions, and it's commendable to go with open-source software all the way. And for a LaTeX writer like me, that's still the fastest way to make a no-frills presentation. But in the end you'll probably have more fun if you give in to the temptations of commercial software. In fact, the open-source route can drive you to despair if your next presentation is your thesis defense and you can't get that Quicktime movie to work on the punchline slide (it's all doable, but with a bit more work, as I describe here).

The beauty of Mac OS X is that PDF is the native format in which things are displayed. This is also true for the commercial program I'm talking about here: Apple's Keynote. The most recent version is '09, but I currently have '08 installed.

You get it as part of the iWork bundle which includes Pages, a nice word processor and layout program; for additional comments see the Pages pages. A newer member of the iWork suite is Numbers, a spreadsheet application. Since I use Mathematica for spreadheet-related tasks (and much more), I may use Numbers even less than Pages. For a user like me who doesn't have Microsoft Office, Numbers could be the most convenient tool to open those Excel files that people sometimes send around by email (faster to start up than NeoOffice).

Back to Keynote:

The Keynote manual (PDF) is here.
The new bitmap transparency capability of Keynote '08 is shown on this page, which also discusses other bitmap programs.

Objectives

I've had some people ask me question about Keynote's features as compared to other presentation software, e.g. Powerpoint. This is not the kind of question I'm focusing on here, though. I'm pushing Keynote here for a very particular type of use, but don't want to tell anyone what to buy, in particular if their intended usage is very different from mine: in short, Keynote functions as a media integration platform, allowing you to put materials produced in various other applications into one package for full-screen presentations, possibly with some nice transition effects added.

To what extent you find Keynote useful or wanting depends on how much you rely on Keynote for actual content production. My general advice would be that content is best produced with other dedicated applications such as Mathematica, a LaTeX system, a graphics program etc. This is the way I use Keynote, and this page is about one aspect of this work flow: the use of LaTeX typesetting with Keynote.

For more information on how to handle specific types of media, such as movies or sound, in Keynote, there is a separate page.

Putting LaTeX into Keyote is a piece of cake. Three different scenarios occur quite frequently:

You have only a PDF file without LaTeX source but want to use parts of it in Keynote
You have a LaTeX document and want to to pick out some equations or text to paste into Keynote
You're making a slide and want to type an equation "on the fly" for use in Keynote

In Powerpoint and Keynote alike, one can always achieve these tasks by going through the first case: create a PDF file, display it in Acrobat Reader (now Adobe Reader), and copy selected parts as bitmaps to paste into the presentation software. To prevent the result from looking grainy, one should first zoom in in the PDF viewer before selecting and copying the desired part (using the graphics copy tool). In the presentation software, you then scale down the pasted image. This creates bitmaps with acceptable resolution but large file size.

Solutions

In Keynote, you can do much better than this. How much better, may depend on your OS version (Jaguar versus Panther). Let's go through the above cases:

The main thing you need is a PDF viewer from which you can copy as PDF, instead of just bitmap format. Adobe Reader does not allow this, but the built-in Preview application does. In Preview version 2.1.0 and above (comes with Tiger), you can actually select arbitrary rectangles within the PDF page and copy them. This, together with its ability to display postscript files as PDF, makes the new version of Preview immensely useful. With the release of Tiger, Preview is at version 3.0. Adobe Reader 7 and 8 have comparable features, but in addition can launch plugins to display additional multimedia content embedded in the file. For this reason, it is still useful to have Adobe Reader installed (in particular if you want to do PDF presentations with Beamer, see below).

How it ought to work:
Shown in the screen shot is an arbitrary area selected in an arbitrary PDF document in the Preview Application (version 2.1.0). To do this, make sure you first activate the Select Tool (press Command-3 or click on the box icon at the top right of the toolbar). If you paste the result into Keynote, it will be in true PDF format. In other words, copying a formula this way, you can scale it, change its opacity, give it shadows, etc.
However, there's a glitch on Leopard:
If you've upgraded to OS X "Leopard", then you're in for an unpleasant surprise: The cropping isn't preserved when pasting into Keynote '08 - this bug is fixed in Keynote '09. For those who still use Keynote '08, I've come up with a work-around for this annoying bug on a separate page. It requires one additional mouse click after copying from Preview, to fix the format of the copied selection.

The screenshot from Keynote shows that the rectangle is faithfully cropped; the result was also scaled and rotated.
Although only the selected part of the original PDF page is displayed in Keynote, the pasted object still contains some information about the discarded parts, so in some cases (for small areas) it can still be more memory-efficient to just copy rectangles as bitmap images (either by screenshot or out of Adobe Reader). The background of a PDF paper often appears transparent in Keynote, meaning that you can choose your own background color by placing a suitably filled rectangle underneath the copied PDF.
In principle, one can also do such manipulations in an automated way. That's particluarly useful if you are copying lots of formulas from a paper but want all of them to appear with the same colored background. The key is that all your copied equations are actually stored in the file that's created when you save the Keynote presentation. For more details, see my remarks on how to change the background color on the LaTeX page.
To put LaTeX into Keynote (as PDF), you need a LaTeX compiler and a Cocoa-based previewer for PDF (this rules out Xwindow programs like gv, but also means you should avoid Adobe Reader). Here are some solutions:
- The path that always works for me starts by compiling a document with PDFLaTeX and opening the result in Preview ≥2.1, and then continuing as in case 1.
- Another path that you may choose is to use the LaTeX environment TeXShop from right here at the University of Oregon (or through the porting system fink). The TexShop Previewer allows you to copy rectangles just as in Preview ≥2.1, and the pasted result in Keynote is a PDF object with all the great advantages like scalability etc.
For immediate editing of formulas "on the fly", there is a great little tool that can use any existing LaTeX installation on your system:
LaTeXiT
1. It's intended to let you type LaTeX source either in a text box or in another prgram (like Pages or TextEdit), and quickly get the typeset result in a variety of useful formats. LaTeXiT tries to inherit the text properties (e.g., color, baseline) of the parent document if one invokes it from the Services menu.
2. Also worth mentioning is the fact that LaTeXiT is linkback aware. What this means can best be seen by experimenting with the Keynote Linkback Plugin written by King Chung Huang. The download location can be found on the main web site of the Linkback Project. After installing this plugin, Keynote 4 (or 3) shows a new menu item "Edit (or refresh) in LaTeXiT" in the Edit menu, whenever you highlight an equation that has been dragged into Keynote from LaTeXiT. If this doesn't show up, make sure you log out and back in again. By using this function from within Keynote, you recover the LaTeX source code for an existing PDF equation in LaTeXit; the modfied PDF will automatically replace the old version on the Keynote slide.
  Warning:
  The linkback plugin may cause problems, and a fix is described below.
  
  For most purposes, LinkBack no longer offers any advantages with Keynote, because LaTeXiT as of version 1.15.0 has the ability to recover the original LaTeX source from a PDF that you paste into it. I.e., you can do the following:
  1. Make an equation in LaTeXiT and copy it into Keynote.
  2. Revisit the Keynote slide at a later time and select that PDF equation again.
  3. Copy the PDF and paste it into the LaTeXiT window. If this PDF was created in LaTeXiT, its original source code re-appears in the editor panel, ready to be modified and copied back to Keynote.
3. Pierre Chatelier, the author of LaTeXiT, also responded very quickly to my requests and comments. The latest addition in response to one of my requests is a keyboard shortcut allowing you to copy the PDF output of LaTeXiT to the Clipboard. LaTeXit is discussed under a different aspect on my Scientific Illustrations page: My contribution to LaTeXit is an algorithm that converts a typeset formula into an outlined (i.e., font-safe) PDF object that will look the same in any application, including Keynote or Adobe Illustrator (I also helped a little with the Pasteboard code).

In conclusion, Apple's Keynote 4 (or 3) comes close to realizing a free-form layout and presentation system in which LaTeX can be integrated almost seamlessly via tools like LaTeXiT. The main gap between the LaTeX and iWork worlds is that styles of the parent document (such as font size) are not inherited by the embedded LaTeX object, so one has to specify them separately on the LaTeX side (which is easy enough to do in the two utilities I mentioned). The LaTeXiT application actually does the best job so far of bridging this gap - at least for Pages, but not yet for Keynote. This is of course a limitation of Keynote, not of LaTeXiT. More on this in the following section.

Caveats, additional utilities

Keynote is a commercial product, and you may or may not feel that you get your money's worth. Keynote essentially serves as a canvas on which many different media styles (text, math, images and movies) can be integrated and presented, as well as exports in various useful formats (e.g., as movies, PDFs or HTML). The added value provided by these programs lies partly in their professional layout and design templates, but that may not be so important to everyone.

However, there are some drawbacks of Keynote. In general, one gets the feeling that Apple is continuing the philosophy of the one-button mouse (adored by some, despised by many) by making the user interface of Keynote really simple-looking. This simplicity sometimes comes at a price when you want to do more complex tasks. Below are some issues that I came across.

A remark about Services: All the nice features of LaTeXiT Services work in Mail or Pages, but not with Keynote: you cannot use the typesetting service within a Keynote text field directly! It's not clear to me why this works in Pages but not in Keynote. The unfortunate consequence of this is that the LaTeX image generated by LaTeXiT (or any other application) does not flow with the regular text in a Keynote slide, and hence formulas have to be repositioned separately from the text if you change, e.g., the width or height of a text field.
There are two ways around this problem:
1. Either type your text together with the formulas in LaTeX - then you don't need Keynote's text fields.
2. Or type simple inline formulas within Keynote by using Unicode characters from a symbol palette. There are several ways to access suitable palettes:
  - Use Keynote's own symbol lists (under the Edit menu) or consult the Character Palette after enabling the International menu bar item.
  - Copy symbols from Mathematica. To make the Unicode symbols work smoothly, it's good to choose Arial Unicode as the text font (if you have it), or stick with something standard like Helvetica.
  - Inline equations without two-dimensional formatting (such as fractions etc.) can also be copied from PDF files directly by using the text selection tool in Preview. The result can be pasted into RTF-capable applications, such as TextEdit, Mail and also Keynote's text fields. This provides a way to get some special symbols into Keynote without using graphics objects. However, since some symbols such as ħ don't get copied properly, you may still have to resort to one of the other options above (or, with a dismissive gesture, claim you've set ħ≡1).
Problems with the Keynote Linkback Plugin
The Linkback Plugin I downloaded from the official web site caused a severe problem with the positioning of grouped objects in Keynote, which showed up only after re-opening a saved presentation.
Solution:
This may have been fixed by the time you read this, but if it isn't, there are instructions for how to fix the problem in this email discussion thread. The culprit is inside the Keynote application bundle, at Keynote.app/Contents/Resources/Animations/K2LinkBackSupport.sfxplugin/Contents/MacOS/K2LinkBackSupport. You should replace this file by a new version which I've archived here. Make sure to download the correct one for your specific processor architecture:
- PowerPC processor
- Intel processor
After installing this fix, I no longer have any problems with misplaced object positions after saving a file.
Problem: There are tools for making drawings within Keynote, but you may want more capabilities
Solution: Some suggestions for software that can fill this gap are
1. Use Adobe Illustrator or a similar graphics application to get all the bells and whistles. This includes the ability to copy and paste directly from Illustrator to Keynote.
2. As a bitmap drawing application, get Seashore, a free program that supports some essential features like gradients and transparency, and is Mac OS X native. If you need a more mature program, consider learning The Gimp (it's X11 software but now has cut and paste interaction with the OS X clipboard). This and other alternatives are discussed on a separate page.
3. If you can't make up your mind which program to use for graphics work, don't worry: no matter how you produce your graphics, there is always the screen capture function. Use either the Grab application or the keyboard shortcut keys listed in the OS X System Preferences, as shown here (for Panther):
  
  The first of these options is an ancient trick from as far back as Mac OS 6 or 7. It creates a file on the Desktop called "Picture 1". The most convenient of these screen capture shortcuts is the last one. It lets you select areas by dragging cross-hairs; and there is a specialized but undocumented bonus feature: when the cross-hairs show up, try pressing the SPACE bar! You suddenly get a "focus-follows-mouse" behavior that highlights any windows or icons you hover over. A mouse click then captures exactly the highlighted object, preserving its dimensions and even its opacity.
  Copying selections to the clipboard produces bitmap images. But under Tiger, you have additional options that let you choose PDF format.
  Here are two ways to get PDF screen shots:
  - If your preferred default setting is bitmap (PNG is the factory setting), you can do PDF screenshots on a case-by-case basis from the Terminal: type screencapture -i -c -t PDF after making sure that the screen area to be captured isn't obscured by the Terminal window. This will launch the screen-capture crosshairs which you drag over the desired rectangle to be copied. The PDF screenshot will be on the Clipboard and can be pasted to Keynote, Preview, GraphicConverter etc.
  - If you want to make PDF format the default screen capture format, then type the following in the Terminal: defaults write com.apple.screencapture type pdf. This can be undone by typing defaults write com.apple.screencapture type png. Other permitted graphics formats are JPG and TIF.

It should be kept in mind that comparisons with Powerpoint (or even OpenOffice) are not really fair because Keynote relies fundamentally on scalable objects both for its fonts and graphics, and if you have worked with vector graphics you know that they are generally a bit harder to manipulate than bitmaps. But this fundamental difference is precisely what makes Keynote superior in the final analysis.

Criticism on the General Equilibrium Theory

porce — Wed, 07 Oct 2009 15:19:05 -0700

This is what I was rooting for:

The long run is a misleading guide to current affairs. In the long run we are all dead. Economists set themselves too easy, too useless a task if in tempestuous seasons they can only tell us that when the storm is past the ocean is flat again.

—John Maynard Keynes, A Tract on Monetary Reform, 1923, Ch. 3

Coast Guard 47' Motor Lifeboat in Morro Bay, CA 04 Dec 2007 by mikebaird

SoCal-NEGT Symposium 2009

porce — Mon, 05 Oct 2009 02:04:48 -0700

SoCal-NEGT Symposium 2009
http://medianetlab.ee.ucla.edu/SocalNEGT/programs.html

Panel Discussion

William Zame's view: Challenges to Nash Equilibrium and Folk Theorem
    - Equilibrium selection: Folk theorem says multiples of Nash can be achieved. But it does not tell which. How would you choose?
    - Uncertainties - how many players, and so on..

Jean Walrand's view
    - We need Robust Game Theory.
    - The outcome of the game is very sensitive to variations of parameters.
    - Let's not solve non-existing games

Steven Low's view
    - Two perspective: Engineering problem using games a a tool, and Engineering problem with economic aspects embedded in.
    - The first kind: TCP manipulation in a massive scale did not occur in last decade. Thus it is not worthwhile to consider this type of game.

J. Ledyard's view:
    - Even though some computations of Nashs are NP hard, let's face the fact. Within the class of the problems, only a small fraction of problems are computationally challenging. Most of the other problems are easy to solve. Thus what's the point of NP hard in reality?

Kerchoff Hall at USC

porce — Thu, 01 Oct 2009 16:35:40 -0700

I am visiting USC for two days for symposium in game theories and economics. Ah, I thought myself as an electrical engineer and now it is amazing that I volunteer to come down to the meetings of this kind. Yeah, the world is changing, and the academia on it is changing too. this old historic building is beautiful as obvious in the picture.